for L being length and w being width
L=5w
perimeter is L+L+w+w or 2L+2w
so we have 2 equations
2L+2w =12
L=5w
in order to solve we need to have the same variable
since we know L is equal to 5w we can just replace L with 5w
2(5w)+2w=12
10w+2w=12
12w=12
divide by 12 on both sides
12w=12
/12 /12
w=1
the width of the rectangle is 1 inch
