An Artist Intends to Paint a 84-Square-Foot Mural on a Wall

Multiple Choice

An artist intends to paint a 84-square-foot mural on a wall that is 18 feet long and 10 feet high. If the artist wants to leave a border of uniform width, how wide should the border be? ( Hint: Let $w$ represent the width of the border. Then $18 - 2 w$ represents the length of the mural.)

A) 1 foot
B) 6 foot
C) 2 foot
D) 14 foot
E) 13 foot