Mathematics: the first application problem (formula is required)

Let team a's speed =x and team b's speed = y.

2x+2.5y= 176- 1

x=3/2y+5

To understand this equation, x=50,

y=30

Team a finished in half an hour 1/24.

That is, 6 hours12/24 =12, that is, team b has 5.5 hours12, so it takes team b1/hour to complete all tasks.

2( 1)(-50-60+20-20+200+75+50- 125)+ 1000*8=8090

8090/8= 10 1 1.25

(2) the one with 20 grams more. Because it is closest to the standard, a little more.

3 A =(x-300)0.8+300

B =(x-200)0.85+200，

When x=500

A =460

B =455, go to B's house.

Solve the equation (x-300)0.8+300=(x-200)0.85+200 to get x=600 A: The cost of buying goods from 600 yuan is the same.