Mary has 3 times as many biscuits as Sarah. The total number of Mary's and Sarah's biscuits is 2 times of Cathy's. Mary and Sarah have 12 biscuits more than Cathy's. How many more biscuits does Mary have than Sarah?
| Mary |
Sarah |
Cathy |
| 3x1 |
1x1 |
|
| 2x2 |
1x2 |
| 3 u |
1 u |
2 u |
The total number of biscuits that Mary and Sarah have is repeated. Make the total number of biscuits that Mary and Sarah have the same. LCM of 4 and 2 is 4.
Total number of biscuits that Mary and Sarah have
= 3 u + 1 u
= 4 u
Number of more biscuits that Mary and Sarah have than Cathy
= 4 u - 2 u
= 2 u
2 u = 12
1 u = 12 ÷ 2 = 6
Number of more biscuits that Mary has than Sarah
= 3 u - 1 u
= 2 u
= 2 x 6
= 12
Answer(s): 12
