Emma and Betty had an equal number of cards at first. Emma used
12 of her cards and Betty used
19 of her cards. They used 99 cards altogether. How many cards did Betty have in the end?
|
Emma |
Betty |
Before |
2x9 = 18 u |
9x2 = 18 u |
Change |
- 1x9 = - 9 u |
- 1x2 = - 2 u |
After |
1x9 = 9 u |
8x2 = 16 u |
The number of cards that Emma and Betty each had at first is the same. Make the number of cards that Emma and Betty each had at first the same. LCM of 2 and 9 is 18.
Number of cards that Emma and Betty used
= 9 u + 2 u
= 11 u
11 u = 99
1 u = 99 ÷ 11 = 9
Number of cards that Betty had in the end
= 16 u
= 16 x 9
= 144
Answer(s): 144