Answer:
180 math tests
Step-by-step explanation:
Let's make a proportion
She can grade 120 math tests in 40 minutes, and x math tests in 60 minutes
test/minutes=test/minutes
120/40=x/60
Cross multiply
120*60=40*x
7200=40x
Since we are trying to find x, we have to get x by itself. 40 and x are being multiplied. To undo this, divide both sides by 40
7200/40=40x/40
180=x
So, she can grade 180 math tests in 60 minutes
