F - Multiply the first terms in each set of parentheses FARTHEST TO THE LEFT
O - Multiply the first term in the first set of parentheses FARTHEST TO THE LEFT by the last term in the second set of parentheses FARTHEST TO THE RIGHT
I - Multiply the last term in the first set of parentheses FARTHEST TO THE RIGHT by the first term in the second set of parentheses FARTHEST TO THE LEFT
L - Multiply the last terms in each set of parentheses FARTHEST TO THE RIGHT
You would take the amount of increase and divide it by the amount of total cost over the time period of certain months. Then you would multiply that number by the percentage of increase gained, and subtract 96.12 to get your answer.