Eva and Mary collected marbles. Mary gave 70% of her marbles to Eva. As a result, Eva's marbles increased by 30%. If Eva had 1092 marbles left, find the total number of marbles the two girls had at first.
| |
Comparing the change
in Mary's marbles |
Mary |
Eva |
| Before |
10x3 =
30 u |
|
10x7 =
70 u |
| Change |
- 7x3 =
- 21 u |
- 3x7 =
- 21 u |
+ 3x7 =
+ 21 u |
| After |
3x3 =
9 u |
|
13x7 =
91 u |
70% =
70100 =
710 30% =
30100 =
310 The number of marbles that Eva gave to Mary is repeated. Make the number of marbles that Eva gave to Mary the same. LCM of 3 and 7 is 21.
Number of marbles that Eva had in the end = 91 u
91 u = 1092
1 u = 1092 ÷ 91 = 12
Number of marbles that Mary and Eva had at first
= 30 u + 70 u
= 100 u
= 100 x 12
= 1200
Answer(s): 1200
