Riordan had 4 times as many grey staplers as gold staplers. After giving away 3 grey staplers and buying another 12 gold staplers, he had an equal number of grey and gold staplers. How many grey staplers did Riordan have at first?
| |
Grey staplers |
Gold staplers |
| Before |
4 u |
1 u |
| Change |
- 3 |
+ 12 |
| After |
4 u - 3 |
1 u + 12 |
The number of grey and gold staplers is the same in the end.
4 u - 3 = 1 u + 12
4 u - 1 u = 12 + 3
3 u = 3 + 12
3 u = 15
1 u = 15 ÷ 3 = 5
Number of grey staplers that Riordan had at first
= 4 u
= 4 x 5
= 20
Answer(s): 20
