David had some pastries.
37 of them were cookies. The rest were shortbreads. He sold
34 of the cookies and 12 shortbreads. In the end, he had 159 pastries left. How many more cookies than shortbreads did he sell?
| |
Cookies |
Shortbreads |
Comparing pastries
at first |
3x4 =
12 u |
4x4 =
16 u |
Before
|
4x3 =
12 u |
16 u |
Change
|
- 3x3 =
- 9 u |
- 12 |
After
|
1x3 =
3 u |
16 u - 12 |
The number of cookies at first is repeated. Make the number of cookies at first the same. LCM of 3 and 4 is 12.
Total number of pastries left
= 3 u + 16 u - 12
= 19 u - 12
19 u - 12 = 159
19 u = 159 + 12
19 u = 171
1 u = 171 ÷ 19 = 9
Number of more cookies than shortbreads that David sold
= 9 u - 12
= 9 x 9 - 12
= 81 - 12
= 69
Answer(s): 69
