Paul had 3 times as many black pencils as gold pencils. After giving away 10 black pencils and buying another 8 gold pencils, he had an equal number of black and gold pencils. How many black pencils did Paul have at first?
| |
Black pencils |
Gold pencils |
| Before |
3 u |
1 u |
| Change |
- 10 |
+ 8 |
| After |
3 u - 10 |
1 u + 8 |
The number of black and gold pencils is the same in the end.
3 u - 10 = 1 u + 8
3 u - 1 u = 8 + 10
2 u = 10 + 8
2 u = 18
1 u = 18 ÷ 2 = 9
Number of black pencils that Paul had at first
= 3 u
= 3 x 9
= 27
Answer(s): 27
