Answer:
x = 14
Explanation:
You can find the perimeter of a rectangle by adding up all the sides. Keep in mind that opposite sides in a rectangle are congruent, which means that the perimeter of a rectangle is essentially 2*length + 2*width. We know the perimeter is 70, the length is x+7, and the width is x, so we can set up the equation to solve for x:
2(x + 7) + 2x = 70
2x + 14 + 2x = 70
4x = 56
x = 14