Explanation: Set up a ratio The percentage of candy bars left is 100 − 70 = 30 Let 30% be the partial percentage. Let 100% be the total percentage. Let x be the partial number of candy bars. Let 20 be the total number of candy bars. 30 100 = x 20 Multiply both sides by 20 30 × 20 100 = x × 20 20 This leaves 600 100 = x Dividing by 100 gives 6 = x