Erika had a collection of 1950 red, blue and green marbles. After Erika gave away 250 red marbles, the number of red marbles was 120 fewer than the number of blue marbles. Given that the number of green marbles was five times as many as the number of blue marbles, how many red marbles did Erika have at first?
| |
Red marbles |
Blue marbles |
Green marbles |
Total |
| Before |
1 u + 250 |
1 u + 120 |
5 u + 600 |
1950 |
| Change |
- 250 |
|
|
|
| After |
1 u |
1 u + 120 |
5 u + 600 |
|
Number of green marbles in the end
= 5 x (1 u + 120)
= 5 u + 600
Total number of marbles at first
= 1 u + 250 + 1 u + 120 + 5 u + 600
= 7 u + 970
7 u + 970 = 1950
7 u = 1950 - 970
7 u = 980
1 u = 980 ÷ 7 = 140
Number of red marbles that Erika had at first
= 1 u + 250
= 140 + 250
= 390
Answer(s): 390
