Tina and Olivia have some cookies each. If Tina gives Olivia 23 cookies, Tina will have
49 as many cookies as Olivia. If Tina gives Olivia 20 cookies, they will have an equal number of cookies. How many cookies does Tina have at first?
|
Case 1 |
Case 2 |
|
Tina |
Olivia |
Tina |
Olivia |
Before |
4 u + 23 |
9 u - 23 |
6.5 u + 20 |
6.5 u - 20 |
Change |
- 23 |
+ 23 |
- 20 |
+ 20 |
After |
4 u |
9 u |
6.5 u |
6.5 u |
Total number of cookies that Tina and Olivia have
= 4 u + 9 u
= 13 u
Number of cookies that Tina and Olivia each has in the end is the same.
Number of cookies that Tina and Olivia each has in the end in Case 2
= 13 u ÷ 2
= 6.5 u
Number of cookies that Tina had at first is the same in Case 1 and Case 2.
6.5 u + 20 = 4 u + 23
6.5 u - 4 u = 23 - 20
0.5 u = 3
1 u = 3 ÷ 0.5 = 6
Number of cookies that Tina has
= 4 u + 23
= 4 x 6 + 23
= 24 + 23
= 47
Answer(s): 47