The space inside the tree is 300 cubic feet
David have to paint 275 square feet on the outside
<em><u>Solution:</u></em>
The tree house is going to 5 feet tall, 8 feet wide, and 7.5 feet long
Length = 7.5 feet
Width = 8 feet
Height = 5 feet
The tree house in the shape of a rectangular prism
<em><u>The volume of rectangular prism is given as:</u></em>

Substituting the values we get,

Thus space inside the tree is 300 cubic feet
<em><u>How much space will they have to paint on the outside?</u></em>
We have to find the surface area of prism
<em><u>The surface area of prism is given as:</u></em>

Substituting the values we get,

Thus they have paint 275 square feet on the outside