Perimeter is 2 x length + 2 x width
We can write that as...
P=2L+2W
We also know the length and perimeter so we substitute and solve like this
90=2 x 27 + 2W
90=54+2W
90-54=54-54+2W (property of subtraction equality)
36=2W
Divide by 2 (property of division equality)
W=18
Thus, the width of the rectangle is 18 cm
