Zoe and Opal have some cookies each. If Zoe gives Opal 11 cookies, Zoe will have
38 as many cookies as Opal. If Zoe gives Opal 7 cookies, they will have an equal number of cookies. How many cookies does Zoe have at first?
| |
Case 1 |
Case 2 |
| |
Zoe |
Opal |
Zoe |
Opal |
| Before |
3 u + 11 |
8 u - 11 |
5.5 u + 7 |
5.5 u - 7 |
| Change |
- 11 |
+ 11 |
- 7 |
+ 7 |
| After |
3 u |
8 u |
5.5 u |
5.5 u |
Total number of cookies that Zoe and Opal have
= 3 u + 8 u
= 11 u
Number of cookies that Zoe and Opal each has in the end is the same.
Number of cookies that Zoe and Opal each has in the end in Case 2
= 11 u ÷ 2
= 5.5 u
Number of cookies that Zoe had at first is the same in Case 1 and Case 2.
5.5 u + 7 = 3 u + 11
5.5 u - 3 u = 11 - 7
0.5 u = 4
1 u = 4 ÷ 0.5 = 8
Number of cookies that Zoe has
= 3 u + 11
= 3 x 8 + 11
= 24 + 11
= 35
Answer(s): 35
