The question in particular is that I am given a rectangle where the length is 2 m less then twice the width. The perimeter is 86 m and I need to find the side length.
I am aware the the answer is that the length is 28 and the width is 15, but I need to show this algebraically. Help would be much obliged.
This is a question about solving a system of (linear) equations, and the techniques are: elimination (multiply equations by nonzero constants and add them) and substitution (solve for a variable and substitute into another equation).
So example of elimination: subtract the second equation from the first to get
2y+2 = 86-y
y = 28
Example of using substitution:
2x + 2(2x - 2) = 86
6x = 90
x = 15