30 + 5h = 20h
30 = 20h - 5h
30 = 15h
30/15 = h
2 = h
at 2 hrs, they both charge the same rate...
30 + 5(2) = 30 + 10 = 40
20h = 20(2) = 40
so at 2 hrs, they both charge $ 40
Let us try and solve it analytically. We have that the side=x+3 together with the short side=s and the diagonal=x+4 satisfy the Pythagorean Theorem. Then we have that

. This yields

which yields s^2=2x+7, hence a) is the correct answer.
9/10 - 5/10
because the denominators are the same you keep it and just subtract the numerators
=4/10
This can be reduced to 2/5
I can't see the pages to be able to help you sorry