There is a batch of goods, which will be transported by car a in 10 hours and by car B in 12 hours. How many hours will it take if car B transports the goods three hours before car a transports the goods?

Party A transports 1 / 10 per hour, and Party B transports 1 / 12 per hour. Party B transports 3 hours first, and can transport 1 / 4. There are 3 / 4 to be transported by Party A, which needs. 3 / 4 divided by 1 / 10 equals 7.5 hours

If a and B are opposite to each other, what is the solution of the equation 3x + 2A = x-2b

A. B is opposite to each other
∴a+b=0
3x+2a=x-2b
2x+2a+2b=0
x+a+b=0
x=0

A pile of yellow sand is five eighths of a ton
How many tons are left after 1 / 4 of transportation
How many tons are left after some are transported
What's left is one fourth more than what's taken away. How many tons are left?

（1）、5/8*(1-1/4)
=(5/8)*(3/4)
=15/32(t)
（2).5/8-5/8*1/4=15/32(t)
(3).(5/8)/(1+1+1/4)
=(5/8)/(9/4)
=5/8*4/9
=5/18(t)

If the line L1: y = (m-1) x + 3 and the line L2: y = 2X-4 intersect the X axis at the same point, the area of the triangle formed by the two lines and the Y axis is calculated

Let the intersection point of L1 and L2 be a (a, 0), then 2a-4 = 0, a = 2, OA = 2
Let L1 and L2 intersect Y axis at B and C respectively, then ob = 3, OC = 4, BC = 7
∴S(△ABC)＝（1/2）｜BC｜｜OA｜＝（1/2）×7×2＝7.
The triangle area of L1, L2 and Y axis is 7

There are three departments in an organ. There are 84 civil servants in department a, 56 civil servants in department B and 60 civil servants in department C. if each department cuts down its staff according to the same proportion and leaves 150 civil servants in this organ, how many civil servants are left in departments a, B and C?

The reduction ratio of the three departments is: 150: (84 + 56 + 60) = 150:200 = 3:4, so the number of staff left by a is: 84 × 34 = 63 (people), the number of staff left by B is: 56 × 34 = 42 (people), the number of staff left by C is: 60 × 34 = 45 (people). A: the number of civil servants left by a, B and C departments is 63, 42 and 45 respectively

Decomposition factor: 9 (m-n) (m-n) + 6m-6n + 1

9(m-n)(m-n)+6m-6n+1
=9(m-n)²+6(m-n)+1
=[3(m-n)]²+2*3(m-n)+1²
=[3(m-n)+1]²
=(3m-3n+1)²

There are 50 students in the school chorus, and the ratio of boys to girls is 2:3. How many boys and girls are there
Formula

2 + 3 = 5 (share) 50 × 2 / 5 = 20 (person) 50 × 3 / 5 = 30 (person)
A: there are 20 boys and 30 girls
Hope to adopt!

The third power of (- A's second power) divided by the fourth power of a

（-a²)³=(-a6)/a4=-a²
Because the minus sign is outside

There are 54 students in class 62, 80% of whom are girls. How many girls are there in class 62

The number of men is x, and that of women is 0.8x
0.8x+x=54
X = 30 people
There are 30 boys and 24 girls

When Xiao Mahu solves the equation 2x-1 / 3 = x + A-1 / 2, he forgets to multiply 6 BY-1 on the right side of the equation when the denominator is removed, so the solution is x = 16. Try to find the value of A

2*2x-1=3(x+a)-6
4x-1=3x+3a-6
3a=4x-3x-1+6
3a=x+5
3a=16+5
3a=21
a=7

There is a batch of goods, which will be transported by car a in 10 hours and by car B in 12 hours. How many hours will it take if car B transports the goods three hours before car a transports the goods?