Question

An electrician cuts a 21 ft piece of wire into two pieces. One piece is 13 ft longer than the shorter piece. How long are the​ pieces?

Answer 1

x = longer piece, y = shorter piece

x + y = 21
x = y + 13

y + 13 + y = 21
2y + 13 = 21
2y = 21 - 13
2y = 8
y = 8/2
y = 4 <=== shorter piece is 4 ft

x = y + 13
x = 4 + 13
x = 17 <== longer piece is 17 ft