Practice!

Sample Problem

Anna, Bruce and Elvis shared a bottle of soda. The ratio of the amount of soda Anna received to the amount Bruce received to the amount Elvis received is 5:7:3. Anna took 80 ml less soda than Bruce. How much of his soda should Bruce give to Elvis so that the three have the same amount in their cups?

ml

Solution

Set the amount of Anna’s soda as 5 units, Bruce’s soda as 7 units and Elvis’s soda as 3 units. So, difference between Anna and Bruce is (7 – 5 = 2) units. Then,

2 units = 80

1 unit = 80 ÷ 5 = 40

Anna: 5 units = 5 × 40 = 200

Bruce: 7 units = 7 × 40 = 280

Elvis: 3 units = 3 × 40 = 120

So, the total amount of soda is 200 + 280 + 120 = 600

If the three of them must have the same amount of soda, the portion for each is: 600 ÷ 3 = 200

Thus, 280 – 200 = 80

Bruce should give 80 ml of soda to Elvis.