<span>First, calculate the difference between 15 and 12. The operation, subtraction, will give us the answer of 3. Then, divide the calculated value by 12 since this it the theoretical length of the nail. Multiply the quotient by 100% to arrive to the final answer. That is (3/12)(100%). The final answer to this item is 25% which is the last choice. </span>
A fact family is basically just different equations with the same numbers getting the same/different numbers as answers you might say... this will make more sense: 5x8=40 8x5=40 40/8=5 40/5=8