Last week, Lee had a total of 103 black and grey notebooks. Two weeks later, he sold
45 of all the black notebooks and bought another 5 grey notebooks. Now he has the same number of black and grey notebooks. How many notebooks does he have in the end?
| |
Black |
Grey |
Total |
| Before |
5 u |
1 u - 5 |
6 u - 5 |
| Change |
- 4 u |
+ 5 |
|
| After |
1 u |
1 u |
|
Comparing the black
and grey notebooks in the end |
1 |
1 |
|
Total number of notebooks at first
= 5 u + 1 u - 5
= 6 u - 5
6 u - 5 = 103
6 u = 103 + 5
6 u = 108
1 u = 108 ÷ 6 = 18
Number of notebooks that he has in the end
= 1 u + 1 u
= 2 u
= 2 x 18
= 36
Answer(s): 36
