Eva had some marble collection.
13 of them were pink and the rest were black. She gave away 105 of the black marbles and 30% of the pink marbles. She then had
15 of her marble collection left. How many marbles did Eva give away?
| |
Pink |
Black |
Total |
Total |
Before
|
1x5 =
5 u |
2x5 =
10 u |
3x5 =
15 u |
5x3 =
15 u |
Change
|
- 0.3x5 =
- 1.5 u |
- 105 |
|
- 4x3 =
- 12 u |
After
|
0.7x5 =
3.5 u |
10 u - 105 |
|
1x3 =
3 u |
The total number of marbles that Eva had at first is repeated. Make the total number of marbles at first the same. LCM 3 and 5 is 15.
Number of pink marbles that Eva gave away
= 30% x 1 u
=
30100 x 1 u
= 0.3 u
1.5 u - 105 = 12 u
12 u - 1.5 u = 105
10.5 u = 105
1 u = 105 ÷ 10.5 = 10
Number of marbles that Eva gave away
= 12 u
= 12 x 10
= 120
Answer(s): 120
