How do I do this math problem?

Question

The entrance to a building is 18 inches off the ground. The wheelchair ramp has a slope of 1/15. How far away from the building does the ramp start?

Answer 1

plug it in to a line prob

x = the distance

y = the height of the door

18= (1/15)x

divide by (1/15)

so 270 = x

270 inches

Answer 2

Same answer as Ken, but i'll elaborate on it.

Let the y-axis be the door, and the x-axis be the ground.

Then the bottom of the entrance is 18, so 18 units up on the y axis is where the ramp will end.

The equation of the line representing the ramp is y = (-1/15)*x + 18

You know the slope is 1/15 (there is a negative there just because of the way I drew the graph), and the y-intercept is 18. So, to find where this line hits the x-axis, i.e. where the ramp starts, we solve for x given y = 0.

We have (1/15)*x = 18 which implies x = 270 inches.

Hope this helps.