The wall measures 7 feet 8 inches across. how far from the edge of the wall do you need to place the nail for it to be centered on the wall

The answer is 3 feet 10 inches.
You need to put the nail in the middle of the wall. To find this, divide 7 feet 8 inches by 2.
First, convert 7 feet 8 inches to just inches. There are 12 inches in a foot, so multiply 7 by 12, then add 8 inches to that. Like this: 7(12)+8=92
So, the wall is 92 inches across. Now, divide 92 by 2,and the answer is 46 (inches). Now, we need to convert this back to feet and inches. We need to divide 46 by 12, then the remainder would be the number of inches and the quotient would be the number of feet. 46/12 = 3, remainder 10. So, it is 3 feet 10 inches. Hence, the nail should be placed 3 feet 10 inches from the edge of the wall.
*this was done with mental math and might have mistakes, please be careful*

The answer simplified would be. -6300x