Part A:
Let the width of the rectangle be = x inches
As given, the length of a rectangle is 3 more inches than the width so let the length of the rectangle be = x+3 inches
Perimeter is given as = 54 inches
Perimeter = 
Equation becomes:
=54

Part B:
Solving the equation we get




Hence, the width of the rectangle is 12 inches
Length = x+3 = 12+3 = 15 inches
Hence, length of the rectangle is 15 inches.