Sean and Andy had some allowance in the ratio of 5 : 11. They shared some money to buy a necklace for their father. The ratio of the amount paid by Sean to the amount paid by Andy was 1 : 3. If Andy was left with $75 and Sean had spent
25 of his money, how much was the necklace they bought?
| |
Sean |
Andy |
| Before |
5 u |
11 u |
| Change |
- 2 u |
- 6 u |
Comparing the
amounts spent |
- 1x2 |
- 3x2 |
| After |
3 u |
75 |
The amount that Sean spent is repeated. Make the amount that Sean spent the same. LCM of 1 and 2 is 2.
Amount that Sean spent
=
25 x 5 u
= 2 u
Amount that Andy spent
= 3 x 2 u
= 6 u
Amount that Andy had left
= 11 u - 6 u
= 5 u
5 u = 75
1 u = 75 ÷ 5 = 15
Price of the necklace
= 2 u + 6 u
= 8 u
= 8 x 15
= $120
Answer(s): $120
