For 25, divide the total bill by the amount paid for each person. 113.58 / 12.62 = 9 exactly, so 9 people attended the party.
For 26, you are given the area and width, and must find the height of the wall. Try making a reverse formula: A=hw, so 128.52=12.6 * h .
Divide 128.52 by 12.6, and you get 10.2 feet as your height (C)
