Japheth, Riordan and Owen had 90 erasers. After Japheth used 9 erasers and Riordan used
34 of her erasers, Japheth had thrice as many erasers left as Riordan. Owen bought another 18 erasers, he had four times the number of erasers Riordan had left. How many erasers did Owen have at first?
| |
Japheth |
Riordan |
Owen |
Total |
| Before |
3 u + 9 |
4 u |
4 u - 18 |
90 |
| Change |
- 9 |
- 3 u |
+ 18 |
|
| After |
3 u |
1 u |
4 u |
|
Comparing Japheth
and Riordan in the end |
3 |
1 |
|
|
Comparing Owen
and Riordan in the end |
|
1 |
4 |
|
Number of erasers that Japheth had in the end
= 3 x 1 u
= 3 u
Number of erasers that Owen had in the end
= 4 x 1 u
= 4 u
Total number of erasers at first
= 3 u + 9 + 4 u + 4 u - 18
= 11 u - 9
11 u - 9 = 90
11 u = 90 + 9
11 u = 99
1 u = 99 ÷ 11 = 9
Number of erasers that Owen had at first
= 4 u - 18
= 4 x 9 - 18
= 36 - 18
= 18
Answer(s): 18
