Xuan and Anna have some wafers each. If Xuan gives Anna 19 wafers, Xuan will have
16 as many wafers as Anna. If Xuan gives Anna 12 wafers, they will have an equal number of wafers. How many wafers does Xuan have at first?
| |
Case 1 |
Case 2 |
| |
Xuan |
Anna |
Xuan |
Anna |
| Before |
1 u + 19 |
6 u - 19 |
3.5 u + 12 |
3.5 u - 12 |
| Change |
- 19 |
+ 19 |
- 12 |
+ 12 |
| After |
1 u |
6 u |
3.5 u |
3.5 u |
Total number of wafers that Xuan and Anna have
= 1 u + 6 u
= 7 u
Number of wafers that Xuan and Anna each has in the end is the same.
Number of wafers that Xuan and Anna each has in the end in Case 2
= 7 u ÷ 2
= 3.5 u
Number of wafers that Xuan had at first is the same in Case 1 and Case 2.
3.5 u + 12 = 1 u + 19
3.5 u - 1 u = 19 - 12
0.5 u = 7
1 u = 7 ÷ 0.5 = 14
Number of wafers that Xuan has
= 1 u + 19
= 1 x 14 + 19
= 14 + 19
= 33
Answer(s): 33
