Risa had some notebooks, staplers and pencils. The ratio of the number of notebooks to the number of staplers was 6 : 1. After giving away 19 staplers, the ratio of the number of pencils to the number of staplers was 3 : 1. Risa bought another 195 pencils. As a result, there were an equal number of notebooks and pencils. How many notebooks did she have at first?
| |
Notebooks |
Staplers |
Pencils |
| Before |
6 u |
1 u |
|
| Change |
|
- 19 |
|
| After 1 |
|
1 u - 19 |
3 u - 57 |
| Change |
|
|
+ 195 |
| After 2 |
6 u |
1 u - 19 |
3 u + 138 |
Number of staplers after Risa gave away 19 staplers
= 1 u - 19
After Risa gave away 19 staplers, the ratio of the number of pencils to the number of staplers became 3 : 1. This means that the number of staplers was 3 times as many as the number of pencils.
Number of pencils after Risa gave away 19 staplers
= 3 x (1 u - 19)
= 3 u - 57
Number of pencils in the end after Risa bought another 195 pencils
= 3 u - 57 + 195
= 3 u + 138
Number of notebooks and pencils in the end is the same.
6 u = 3 u + 1386 u - 3 u = 1383 u = 138
1 u = 138 ÷ 3 = 46
Total numbers of notebooks that Risa had at first
= 6 u
= 6 x 46
= 276
Answer(s): 276
