8 ft= ___ inches
1 ft= 12 inches
8 ft= 12 x 8 inches
8 ft=96 inches
She has 96 inches, but she needs 100 inches. So she needs 4 more inches of lumber.
the answer to your equation is
n=40
The park is a total of 3+3 = 6 miles east of the mall, and 4+5=9 miles north of it. The Pythagorean theorem tells you the straight-line distance in miles is
√(6² +9²) = √117 ≈ 10.8