Hi there! :)
Find the perimeter by solving for y.
We know that a rectangle contains two pairs of parallel and congruent sides, therefore:
5y - 1 = 2y + 8
We can solve for y using this expression. Begin by subtracting 2y from both sides:
5y - 2y - 1 = 2y - 2y + 8
3y - 1 = 8
Add 1 to both sides:
3y - 1 + 1 = 8 + 1
3y = 9
Divide both sides by 3:
y = 3
Recall that the perimeter of a rectangle is:
P = 2l + 2w
Plug in the given expressions for the side lengths to find one equation:
P = 2(5y - 1) + 2(y - 1)
Simplify by distribution:
P = 10y - 2 + 2y - 2
Combine like terms:
P = 12y - 4
Plug in the solved value of y into this equation:
P = 12(3) - 4
P = 36 - 4
P = 32 cm.