Answer:
She spent 5 hours mowing lawns.
Explanation:
To solve, we will just use some algebra
8h + 20 = 60 | Subtract 20 from both sides
8h = 40 | Divide both sides by 8
h = 5
We can confirm this by plugging it back into the original formula.
8(5) + 20 = 60
40 + 20 = 60
60 = 60