Question 21762
First you must have the formula for perimeter of a rectangle
P=2L + 2W
you have the length and the perimeter values, so plug them into the formula

26 = 2(9)+2W
26 = 18 + 2w
26-18 = 2w
8= 2w
4=w

check your work by plugging the numbers into the formula
26= 2(9) + 2(4)
26=18 + 8
26=26