In a shop, the number of cartons of starfruit juice sold was
13 the number of cartons left. When 81 more cartons were sold, the total number of cartons sold was 9 less than
78 the number of cartons the shop had at first. How many cartons were there at first?
|
Sold |
Left |
Total |
Before |
1x2 = 2 u |
3x2 = 6 u |
4x2 = 8 u
|
Change |
+ 81 |
- 81 |
|
After |
2 u + 81 |
6 u - 81 |
8 u |
Comparing the total number of cartons sold and the total number of cartons at first |
7x1 - 9 = 7 u - 9 |
|
8x1 = 8 u |
The total number of cartons is repeated. Make the total number of cartons the same. LCM of 4 and 8 is 8.
The number of cartons sold in the end is repeated.
7 u - 9 = 2 u + 81
7 u - 2 u = 81 + 9
5 u = 90
1 u = 90 ÷ 5 = 18
Number of cartons at first
= 8 u
= 8 x 18
= 144
Answer(s): 144