In a shop, the number of cartons of grapefruit juice sold was
12 the number of cartons left. When 30 more cartons were sold, the total number of cartons sold was 10 less than
47 the number of cartons the shop had at first. How many cartons were there at first?
|
Sold |
Left |
Total |
Before |
1x7 = 7 u |
2x7 = 14 u |
3x7 = 21 u
|
Change |
+ 30 |
- 30 |
|
After |
7 u + 30 |
14 u - 30 |
21 u |
Comparing the total number of cartons sold and the total number of cartons at first |
4x3 - 10 = 12 u - 10 |
|
7x3 = 21 u |
The total number of cartons is repeated. Make the total number of cartons the same. LCM of 3 and 7 is 21.
The number of cartons sold in the end is repeated.
12 u - 10 = 7 u + 30
12 u - 7 u = 30 + 10
5 u = 40
1 u = 40 ÷ 5 = 8
Number of cartons at first
= 21 u
= 21 x 8
= 168
Answer(s): 168