Xuan had a total of 229 red and blue marbles. She used
45 of her red marbles and bought another 57 blue marbles. The number of blue marbles she had then become
15 the number of red marbles. How many less blue marbles than red marbles did she have at first?
|
Red marbles |
Blue marbles |
Before |
5x5 |
|
Change |
- 4x5 |
+ 57 |
After |
1x5 |
|
Comparing marbles in the end |
5x1 |
1x1 |
|
Red marbles |
Blue marbles |
Before |
25 u |
1 u - 57 |
Change |
- 20 u |
+ 57 |
After |
5 u |
1 u |
The number of red marbles in the end is repeated.
LCM of 1 and 5 is 5.
Total number of red marbles and blue marbles
= 25 u + 1 u - 57
= 26 u - 57
26 u - 57 = 229
26 u = 229 + 57
26 u = 286
1 u = 286 ÷ 26 = 11
Number of less blue marbles than red marbles at first
= 25 u - (1 u - 57)
= 24 u + 57
= 24 x 11 + 57
= 321
Answer(s): 321