
Chad S. answered 12/14/18
Level III Master Certified Tutor Specializing in Math and Science
Hello Vero!
The perimeter of a rectangle is P = 2L + 2W where L is the length and W is the width
We are given the perimeter and a relationship between length and width.
[1] 324 = 2L + 2W
We have to convert the relationship between the length and the width into words, which is the trickiest part of this problem. The relationship mathematically is:
[2] W = .5L - 6
We have two equations and two unknowns, so we can plug W from [2] into [1] and solve for L.
324 = 2L + 2(.5L - 6)
Solving for L we get:
[3] L = 112 inches
For the final step, we can plug L from [3] into [1] to get W
324 = 2(112) + 2W
Solving for W we get:
[4] W = 50 inches
Since we should always check our answers, we can plug in the Length and Width into the first equation.
324 = 2(112) + 2(50) = 324
Let me know if you need further clarification :)