Question

How many feet of baseboards will Zach need? (The side with the question mark should be 5 ft.)

Answer 1

5 ft

1) Note that in a blueprint all the angles of that figure are 90º. So we can tell that there are parallel lines.

2) Therefore, we can tell that Zach will need 5 ft of baseboards

Because that 5 plus 10 makes 15 ft, the length of that upper side of the bedroom.