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Tinplate can be made, each tinplate can be made into 25 boxes or 40 boxes, and two boxes in a box can be made into a set of cans. At present, there are 36 pieces of iron. How many tinplates does it take to make the box match the bottom of the box?
Analysis: Because there are always 36 iron boxes, x+y=36. Formula; The number of sheets made in the box+the number of sheets made at the bottom of the box = the total number of sheets made in cans * * * 36. The equation (1) is obtained. Because now a box body and two box bottoms are made into a set of cans, so; Number of boxes *2= number of box bottoms. This will make them equal. Equation (2)2* 16x=40y is obtained.
x+y=36 ( 1)
2* 16x=40y (2)
36-y=x (3) from ( 1)
Substituting (3) into (2) to obtain;
32(36-y)=40y
y= 16
If y= 16 is substituted (1), then x=20.
So; x=20
y= 16
Answer: Use 20 sheets as the box, and 16 as the bottom.
Now the total age of parents is six times that of children; Two years ago, the sum of parents' age and children's age was 10 times of children's age; The combined age of parents is three times that of children. Q: * * * When will the baby be born?
The sum of parents' ages is X, the sum of children's ages is Y, and there are n children.
X=6Y
(X-4)= 10(Y-n*2)
6Y-4= 10Y-20N
4Y=20N-4
Y=5N- 1
(X+ 12)=3(Y+n*6)
6Y+ 12=3Y+ 18N
3Y= 18N- 12
Y=6N-4
6N-4=5N- 1
N=3
I have three children.
Party A and Party B set out from A and A respectively and face to face at the same time. They met for the first time 50 kilometers away from the midpoint of Party A, and turned back immediately after arriving at B and A. As a result, Party A and Party B met for the second time at a distance of A 100 meters to find the distance between A and B..
Two people, A and B, set out from A to B, A can't, and B can ride a bike. If A walks 6 kilometers, they will arrive at B at the same time 45 minutes after B leaves. If A takes 1 poem first and B catches up with A half an hour after departure, find the distance between A and B. 。
Let the speed of a be a km/h and the speed of b be b km/h.
45 minutes =3/4 hours
6+3/4a=3/4b
a=(b-a)x 1/2
simplify
b-a=8( 1)
3a=b(2)
( 1)+(2)
2a=8
A=4 km/h
B = 3x4 =12km/h
AB distance = 12x 3/4 = 9 km.
The factory is connected with A and B by roads and railways. Our factory purchased a batch of raw materials with a price of 1 1,000 yuan a ton from Party A and transported them to Party B. It is known that the road freight rate 1.5 yuan/(ton, km) and the railway freight rate 1.2 yuan/(ton, km), these two transports *.
Dong Zhang went to the department store to buy two kinds of envelopes, ***30, of which 1 yuan is 50 cents for an A-type envelope, 1 yuan is 50 cents for a B-type envelope, and B-type envelopes are 20 cents cheaper than A-type envelopes. What is the unit price of these two kinds of envelopes?
Let the unit price of type A envelope be one point, and that of type B envelope be -2 points.
If you buy a B-type A envelope, you will buy a 30-b-type B envelope.
1 yuan.50 = 150.
ab= 150( 1)
(a-2)(30-b)= 150(2)
By (2)
30a-60-ab+2b= 150
Substitution (1)
30a- 150+2b=2 10
30a+2b=360
15a+b= 180
b= 180- 15a
Replace (1)
a( 180- 15a)= 150
Answer? - 12a+ 10=0
(a-6)？ =36- 10
a-6= √26
a=6 √26
A 1≈ 1 1 min, then the b-type envelope 1 1-2=9 points.
A2≈0.9, then 0.9-2=- 1. 1 of the type B envelope is irrelevant, so it is discarded.
The unit price of type A is 1 1, and that of type B is 9.
In 2003, the Ministry of Finance issued 3-year and 5-year certificate-type treasury bills of 50,000 yuan. If the interest earned by the five-year Treasury bill after maturity is 2553 yuan, what are the interests of the two kinds of Treasury bills?
There are a flock of pigeons, some are singing in the trees, others are on the ground. A pigeon in the tree said to the pigeon on the ground, "If one flies down from the tree, there will be as many pigeons in the tree as there are under it." Do you know how many pigeons are on and under the tree?
It is known that a railway bridge is 1000 meters long and a train passes through it. It takes 1 minute for the train to get on the bridge from the start point to the end point, and the whole train stays on the bridge for 40 seconds. What about the speed and length of the train?
Let the train speed be one meter per second and the car body length be b meters.
1 min =60 seconds
60a= 1000+b
40a= 1000-b
100a=2000
A = 20m m/s
b=60x20- 1000
B=200 meters
The car body is 200 meters long and the speed is 20 meters per second.