To find the length of the side of the original square, we can follow these steps:
1. Let x represent the length of a side of the original square.
2. If the length of a side of the square is increased by 5, the new length becomes x + 5.
3. The perimeter of a square is calculated by adding up all the sides, which for a square is 4 times the length of one side.
4. Given that the perimeter of the new square is 60, we can set up the equation: 4(x + 5) = 60.
5. Simplifying the equation gives us 4x + 20 = 60.
6. Next, we solve for x by isolating it on one side of the equation.
7. Subtracting 20 from both sides, we get 4x = 40.
8. Finally, divide both sides by 4 to find the length of the side of the original square: x = 10.
Therefore, the correct equation to find the length of the side of the original square is:
A. 4(x + 5) = 60
