Tiffany and Betty had an equal number of pens at first. Tiffany used
14 of her pens and Betty used
17 of her pens. They used 55 pens altogether. How many pens did Betty have in the end?
|
Tiffany |
Betty |
Before |
4x7 = 28 u |
7x4 = 28 u |
Change |
- 1x7 = - 7 u |
- 1x4 = - 4 u |
After |
3x7 = 21 u |
6x4 = 24 u |
The number of pens that Tiffany and Betty each had at first is the same. Make the number of pens that Tiffany and Betty each had at first the same. LCM of 4 and 7 is 28.
Number of pens that Tiffany and Betty used
= 7 u + 4 u
= 11 u
11 u = 55
1 u = 55 ÷ 11 = 5
Number of pens that Betty had in the end
= 24 u
= 24 x 5
= 120
Answer(s): 120