In a shop, the number of cartons of persimmon juice sold was
12 the number of cartons left. When 90 more cartons were sold, the total number of cartons sold was 9 less than
710 the number of cartons the shop had at first. How many cartons were left?
| |
Sold |
Left |
Total |
| Before |
1x10 =
10 u |
2x10 =
20 u |
3x10 =
30 u
|
| Change |
+ 90 |
- 90 |
|
| After |
10 u + 90 |
20 u - 90 |
30 u |
Comparing the total
number of cartons
sold and the total number of cartons at first |
7x3 - 9 =
21 u - 9 |
|
10x3 =
30 u |
The total number of cartons is repeated. Make the total number of cartons the same. LCM of 3 and 10 is 30.
The number of cartons sold in the end is repeated.
21 u - 9 = 10 u + 90
21 u - 10 u = 90 + 9
11 u = 99
1 u = 99 ÷ 11 = 9
Number of cartons left
= 20 u - 90
= 20 x 9 - 90
= 180 - 90
= 90
Answer(s): 90
