Perimeter length help

Question

Rectangle with perimeter of 126 ft, length is 3 more than five times the width, what is the width

Answer 1

Suppose that x is the length and y the width. Then the perimeter is given by 2x+2y=126. We also have that x=3+5y which if we plug in the first equation we obtain that 2(3+5y)+2y=126 which is the same as 6+12y=126 or 12y=120 or y=10.