15 days ago, Gem had a total of 300 green and brown marbles. 30% of her marbles were brown marbles. Today, her older brother gave her some more marbles. As a result, her green marbles increased by 10%. Now, 50% of her marbles are brown marbles. How many brown marbles did her older brother give her?
| |
Brown marbles |
Green marbles |
Total
marbles |
| Before |
3 u |
7 u |
300 |
| Change |
+ 4.7 u |
+ 0.7 u |
|
| After |
7.7 u |
7.7 u |
|
Comparing the
green marbles and
brown marbles in the end |
1 |
1 |
|
30% =
30100 =
310 Brown marbles : Green marbles = 3 : 7
Increase in the number of green marbles
= 10% x 7 u
=
10100 x 7 u
= 0.7 u
50% =
50100 =
12 In the end
Brown marbles : Green marbles = 1 : 1
Number of marbles at first
= 7 u + 3 u
= 10 u
10 u = 300
1 u = 300 ÷ 10 = 30
Number of brown marbles that Gem received from her older brother
= 7.7 u - 3 u
= 4.7 u
= 4.7 x 30
= 141
Answer(s): 141
