Chapter 1 - Equations and Inequalities - 1.2 Applications and Modeling with Linear Equations - 1.2 Exercises - Page 101: 14

$b=12.7$ cm

The perimeter of a rectangle can be calculated as: $P=2a+2b$ where a and b are the width and the length of the rectangle. Here: $b=2a-2.5$, $P=40.6$ cm By substituting we get: $40.6=2a+2(2a-2.5)=2a+4a-5=6a-5$ $40.6=6a-5$ $6a=45.6$ $a=7.6$ cm $b=2a-2.5=2(7.6)-2.5=12.7$ cm