David, Charlie and Pierre had 190 pencils. After David used 8 pencils and Charlie used
25 of her pencils, David had thrice as many pencils left as Charlie. Pierre bought another 18 pencils, he had twice the number of pencils Charlie had left. How many pencils did Pierre have at first?
| |
David |
Charlie |
Pierre |
Total |
| Before |
9 u + 8 |
5 u |
6 u - 18 |
190 |
| Change |
- 8 |
- 2 u |
+ 18 |
|
| After |
9 u |
3 u |
6 u |
|
Comparing David
and Charlie in the end |
3 |
1 |
|
|
Comparing Pierre
and Charlie in the end |
|
1 |
2 |
|
Number of pencils that David had in the end
= 3 x 3 u
= 9 u
Number of pencils that Pierre had in the end
= 2 x 3 u
= 6 u
Total number of pencils at first
= 9 u + 8 + 5 u + 6 u - 18
= 20 u - 10
20 u - 10 = 190
20 u = 190 + 10
20 u = 200
1 u = 200 ÷ 20 = 10
Number of pencils that Pierre had at first
= 6 u - 18
= 6 x 10 - 18
= 60 - 18
= 42
Answer(s): 42
