Andy and Billy had some allowance in the ratio of 5 : 8. They shared some money to buy a necklace for their nephew. The ratio of the amount paid by Andy to the amount paid by Billy was 1 : 3. If Billy was left with $56 and Andy had spent
25 of his money, how much was the necklace they bought?
| |
Andy |
Billy |
| Before |
5 u |
8 u |
| Change |
- 2 u |
- 6 u |
Comparing the
amounts spent |
- 1x2 |
- 3x2 |
| After |
3 u |
56 |
The amount that Andy spent is repeated. Make the amount that Andy spent the same. LCM of 1 and 2 is 2.
Amount that Andy spent
=
25 x 5 u
= 2 u
Amount that Billy spent
= 3 x 2 u
= 6 u
Amount that Billy had left
= 8 u - 6 u
= 2 u
2 u = 56
1 u = 56 ÷ 2 = 28
Price of the necklace
= 2 u + 6 u
= 8 u
= 8 x 28
= $224
Answer(s): $224
