If the side of a square is doubled and then increased by 7, the new perimeter is 8 more then 3 times the old perimeter. What is the side of the original square?
Let the side of the original square be x. The perimeter is 4x. The new side of the square is 2x+7 and the new perimeter is 4(2x+7)=8x+28. So 8x+28=12x+8. 4x=20, so x=5, the side of the original square.
