In a shop, the number of cartons of lemon juice sold was
12 the number of cartons left. When 15 more cartons were sold, the total number of cartons sold was 5 less than
79 the number of cartons the shop had at first. How many cartons were there at first?
|
Sold |
Left |
Total |
Before |
1x3 = 3 u |
2x3 = 6 u |
3x3 = 9 u
|
Change |
+ 15 |
- 15 |
|
After |
3 u + 15 |
6 u - 15 |
9 u |
Comparing the total number of cartons sold and the total number of cartons at first |
7x1 - 5 = 7 u - 5 |
|
9x1 = 9 u |
The total number of cartons is repeated. Make the total number of cartons the same. LCM of 3 and 9 is 9.
The number of cartons sold in the end is repeated.
7 u - 5 = 3 u + 15
7 u - 3 u = 15 + 5
4 u = 20
1 u = 20 ÷ 4 = 5
Number of cartons at first
= 9 u
= 9 x 5
= 45
Answer(s): 45