length = 68 cm and width = 10 cm
let w represent the width then length = 7w - 2
perimeter = 2(length + width) = 2(7w - 2 + w)= 2(8w - 2) = 16w -4
we are given perimeter = 156 thus
16w - 4 = 156 → (solve for w)
add 4 to both sides
16w = 156 + 4 = 160
divide both sides by 16
w = [tex]\frac{160}{16}[/tex] = 10
thus width = 10 cm and length = (7 × 10) - 2 = 70 - 2 = 68 cm
