Decrease 40 by 62 1/2%

15

Step-by-step explanation:

Take 62.5 from 100  = 37.5

divide this by 100 = 0.375

times 40 by this

0.375 x 40 = 15

For each t-shirt sold, which I'll call t, 8th grade makes $15.

For each hat sold, which I'll call h, 8th grades makes $5.

They want to raise $900

A: The equation to represent this situation is 15t+5h=900 because if 8th grade adds up all the profits from both hats and t-shirts, the goal is to make $900, so the total profit from shirts and hats should equal 900 dollars.

B: I'm just going to choose random numbers. Let's say nobody wanted to buy a hat from the 8th graders (h=0). You'd end up with

15t+5(0)=900

15t=900

t=60 - If they sold 0 hats they would have sold 60 shirts to raise $900

Now let's say it was the other way around - nobody wanted to buy t-shirts

15(0)=5h=900

5h=900

h=180 - If they sold 0 t-shirts they'd have to sell 180 hats to raise $900

Finally let's say they sold 30 t-shirts

15(30)+5h=900

450+5h=900

5h=450

h=90 - They'd have to sell 30 t-shirts and 90 hats to raise $900