Question 28324
The length of a rectangle is 3 in. more than twice its width.  If the perimeter of the rectangle is 18 in., find the width of the rectangle.
Let the length of the rectangle be a inches
and the width be b inches
Length is 3 inches more than twice its width.
a is 3 inches more than  twice b
a is greater than 2b by 3
a-2b = 3 ----(1)
Perimeter of the rectangle is 18 inches.
That is 2(a+b) = 18
(a+b) =9 ----(2)
(2) - (1) implies
(a-a)+[b-(-2b)] = (9-3)
0 +(b+2b) = 6
3b=6
b= 6/3 = 2
b=2 in (2) is a+b = 9
a + 2 = 9
a = 9-2 = 7
Therefore length is 7inches and width is 2 inches
Verification:
Length should be 3 more than twice width
And  of course 7 is 3 more than twice 2
Perimeter: 2(length+width) = 2X(7+2) = 2X9 = 18 which is correct.