Wendy and Sarah have some puffs each. If Wendy gives Sarah 21 puffs, Wendy will have
38 as many puffs as Sarah. If Wendy gives Sarah 19 puffs, they will have an equal number of puffs. How many puffs does Wendy have at first?
| |
Case 1 |
Case 2 |
| |
Wendy |
Sarah |
Wendy |
Sarah |
| Before |
3 u + 21 |
8 u - 21 |
5.5 u + 19 |
5.5 u - 19 |
| Change |
- 21 |
+ 21 |
- 19 |
+ 19 |
| After |
3 u |
8 u |
5.5 u |
5.5 u |
Total number of puffs that Wendy and Sarah have
= 3 u + 8 u
= 11 u
Number of puffs that Wendy and Sarah each has in the end is the same.
Number of puffs that Wendy and Sarah each has in the end in Case 2
= 11 u ÷ 2
= 5.5 u
Number of puffs that Wendy had at first is the same in Case 1 and Case 2.
5.5 u + 19 = 3 u + 21
5.5 u - 3 u = 21 - 19
0.5 u = 2
1 u = 2 ÷ 0.5 = 4
Number of puffs that Wendy has
= 3 u + 21
= 3 x 4 + 21
= 12 + 21
= 33
Answer(s): 33
