length = 32 and width = 5
let the width = w then length = 4w + 12
perimeter = 2 ( length + width )
= 2( 4w + 12 + w ) = 2( 5w + 12 ) = 10w + 24
perimeter = 74
solve 10w + 24 = 74
subtract 24 from both sides
10w = 74 - 24 = 50 ⇒ w = 5
width = 5 and length = (4 × 5) + 12 = 20 + 12 = 32
