Last week, Tommy had a total of 221 purple and red pencils. Two weeks later, he sold
23 of all the purple pencils and bought another 3 red pencils. Now he has the same number of purple and red pencils. How many pencils does he have in the end?
| |
Purple |
Red |
Total |
| Before |
3 u |
1 u - 3 |
4 u - 3 |
| Change |
- 2 u |
+ 3 |
|
| After |
1 u |
1 u |
|
Comparing the purple
and red pencils in the end |
1 |
1 |
|
Total number of pencils at first
= 3 u + 1 u - 3
= 4 u - 3
4 u - 3 = 221
4 u = 221 + 3
4 u = 224
1 u = 224 ÷ 4 = 56
Number of pencils that he has in the end
= 1 u + 1 u
= 2 u
= 2 x 56
= 112
Answer(s): 112
