Perimeter is 140 meters, length is 30 meters greater than the width. How do I Find the dimensions

Well I am assuming this is a rectangle. in a rectangle:

perimeter = 2 * width + 2 * length

We are told that:

length = width + 30

We can substitute out known value for length into the top equation:

perimeter = 2 * width + 2 * length

perimeter = 2 * width + 2 * (width + 30)

We are told that:

perimeter = 140

We can also sub that in:

perimeter = 2 * width + 2 * (width + 30)

(140) = 2 * width + 2 * (width + 30)

(140) = 2w + 2w + 60

80 = 4w

20 = w

We know width and we can sub in for our 2nd equation we made above:

length = width + 30

length = 20 + 30

l = 50

We can check by plugging in our answers to the top equation:

perimeter = 2 * width + 2 * length

140 = 2 * 20 + 2 * 50

140 = 140

it is correct