Barbara had a total of 400 pink and black balls. She used
37 of her pink balls and bought another 50 black balls. The number of black balls she had then become
13 the number of pink balls. How many less black balls than pink balls did she have at first?
| |
Pink balls |
Black balls |
| Before |
7x3 |
|
| Change |
- 3x3 |
+ 50 |
| After |
4x3 |
|
| Comparing balls in the end |
3x4 |
1x4 |
| |
Pink balls |
Black balls |
| Before |
21 u |
4 u - 50 |
| Change |
- 9 u |
+ 50 |
| After |
12 u |
4 u |
The number of pink balls in the end is repeated.
LCM of 4 and 3 is 12.
Total number of pink balls and black balls
= 21 u + 4 u - 50
= 25 u - 50
25 u - 50 = 400
25 u = 400 + 50
25 u = 450
1 u = 450 ÷ 25 = 18
Number of less black balls than pink balls at first
= 21 u - (4 u - 50)
= 17 u + 50
= 17 x 18 + 50
= 356
Answer(s): 356
