Step 1: Find the Lowest Common Multiple between the denominators.
Step 2: Multiply the numerator and denominator of each fraction by a number (the one that will get them to the lcm) so that they have the LCM as their new denominator.
Step 3: Add or subtract the numerators and keep the denominator the same.
To find a percentage of a number, multiply by the decimal form of that percentage(20%=0.20). So, take the cost, $430, and multiply by common state sales tax (7% for me)---430 x 0.07 = 30.10 The sale tax rate is 7%.
To get the answer, first, you must find the amount in each box, so you must divide, 122 divided by 8, you should get 15.25, but that's not your answer. The question asks how many COMPLETE boxes, so just choose the whole number, which is 15. 15 is the answer.