Answer:
Trenton needs 21 square feet of plywood to cover all the surface of the ramp.
Explanation:
Givens
- Base is 2 feet long.
- Height is 1.5 feet long.
- Length is 3 feet long.
- The riding surface is 2.5 feet long.
Notice that the ramp is formed by two triangles and three rectangles.
Each triangle has a base of 2 feet and a height of 1.5 feet. So, the area of each triangle is

The base of the ramp has dimensions of 3 feet x 2 feet. Its are is

The back of the ram has an area of

The riding surface is

So, basically, to know the total surface, we just have to sum the are of both triangles, and the area of all three rectangles, as follows

This means that Trenton needs 21 square feet of plywood to cover all the surface of the ramp.