PSLE At a sale, Billy bought 8 mugs of the same kind. His sister bought 6 such mugs. She also bought 3 glasses at $7.70 each. Altogether, she spent $10.70 more than Billy. What was the total amount of money Billy and his sister spent?
|
Billy |
His sister |
Items bought
|
8 mugs
|
6 mugs + 3 glasses = 6 mugs + 23.10 |
Comparing the amounts paid |
|
$10.70 more |
Amount that his sister spent on 3 glasses
= 3 x 7.70
= $23.10
Let the cost of 1 mug be 1 M.
If Billy's sister spent $10.70 less, each would pay the same amount.
8 M + 10.70 = 6 M + 23.10 - 10.70
8 M - 6 M = 23.10 - 10.70
2 M = 12.40
1 M = 12.40 ÷ 2 = 6.20
Total amount that Billy and his sister spent
= 8 M + 6 M + 23.10
= 14 M + 23.10
= 14 x 6.20 + 23.10
= 86.80 + 23.10
= $109.90
Answer(s): $109.90