Sam, Lee and Justin had 320 coins. After Sam used 13 coins and Lee used
15 of her coins, Sam had four times as many coins left as Lee. Justin bought another 23 coins, he had thrice the number of coins Lee had left. How many coins did Justin have at first?
| |
Sam |
Lee |
Justin |
Total |
| Before |
16 u + 13 |
5 u |
12 u - 23 |
320 |
| Change |
- 13 |
- 1 u |
+ 23 |
|
| After |
16 u |
4 u |
12 u |
|
Comparing Sam
and Lee in the end |
4 |
1 |
|
|
Comparing Justin
and Lee in the end |
|
1 |
3 |
|
Number of coins that Sam had in the end
= 4 x 4 u
= 16 u
Number of coins that Justin had in the end
= 3 x 4 u
= 12 u
Total number of coins at first
= 16 u + 13 + 5 u + 12 u - 23
= 33 u - 10
33 u - 10 = 320
33 u = 320 + 10
33 u = 330
1 u = 330 ÷ 33 = 10
Number of coins that Justin had at first
= 12 u - 23
= 12 x 10 - 23
= 120 - 23
= 97
Answer(s): 97
