Emma had a collection of 1900 gold, black and blue marbles. After Emma gave away 280 gold marbles, the number of gold marbles was 210 fewer than the number of black marbles. Given that the number of blue marbles was four times as many as the number of black marbles, how many gold marbles did Emma have at first?
| |
Gold marbles |
Black marbles |
Blue marbles |
Total |
| Before |
1 u + 280 |
1 u + 210 |
4 u + 840 |
1900 |
| Change |
- 280 |
|
|
|
| After |
1 u |
1 u + 210 |
4 u + 840 |
|
Number of blue marbles in the end
= 4 x (1 u + 210)
= 4 u + 840
Total number of marbles at first
= 1 u + 280 + 1 u + 210 + 4 u + 840
= 6 u + 1330
6 u + 1330 = 1900
6 u = 1900 - 1330
6 u = 570
1 u = 570 ÷ 6 = 95
Number of gold marbles that Emma had at first
= 1 u + 280
= 95 + 280
= 375
Answer(s): 375
