The question:

Suppose a ramp is used to move a heavy object into a van. Suppose also that the van door is 18 inches off the ground.

(a) If the bottom of the ramp rests on the ground 3 feet from the van, what is the slope of the ramp? (Round your answer to two decimal places.)

6 in/ft (I've answered this already... says its right.)

(b) If the ramp cannot have a slope of more than 1.3 inches per foot, how far from the van should the ramp rest? (Round your answer to two decimal places.)

____ ft

I don't understand what it means... I got 11.53, but that's wrong.