Abi had 15 more cards than Sarah. After Sarah gave away
47 of her cards, Abi had four times as many cards as Sarah. How many cards did Sarah have at first?
| |
Abi |
Sarah |
Comparing Abi and
Sarah at first |
15 more |
|
| Before |
12 u |
7 u |
| Change |
|
- 4 u |
| After |
12 u |
3 u |
Comparing Abi and
Sarah in the end |
4x3 =
12 u |
1x3 =
3 u |
Number of cards that Sarah had in the end is repeated. Make the number of cards that Sarah had in the end the same. LCM of 1 and 3 is 3.
Number of cards that Abi had at first = 12 u
Number of cards that Abi had more than Sarah at first
= 12 u - 7 u
= 5 u
5 u = 15
1 u = 15 ÷ 5 = 3
Number of cards that Sarah had at first
= 7 u
= 7 x 3
= 21
Answer(s): 21
