Question

A rectangle has a perimeter of 54cm. the length is 16 cm . what is the width of the rectangle?

Answer 1

w= 27/8 (3 3/8 as a mixed number) or if you would like to write it as a decimal w=3.375 

Answer 2

P=2(a+b)
54=2(16+b)
54=32+2b
22=2b
11=b

The width is 11cm.

Just say if you need a better explanation.