Answer:
x = 4 in
Step-by-step explanation:
You want the value of x if the perimeter of a rectangle with length 5x and width x-3 is 42 inches.
Perimeter
The perimeter can be found using the formula ...
P = 2(L +W)
Using the given values, this becomes ...
42 = 2(5x +x -3)
21 = 6x -3 . . . . . . . . . . divide by 2
24 = 6x . . . . . . . . . add 3
4 = x . . . . . . . . . divide by 6
The value of x is 4 inches.
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Additional comment
For the value of x to be 4 inches, the number 3 in the given width dimension must actually be 3 inches. We can only add or subtract values that have the same units. (One could say to the teacher, "don't forget your units!")
