There are 130 marbles in a basket. 0.1 of them are green marbles, and the rest are black and grey marbles. If there are 18 as many black marbles as grey marbles. How many grey marbles are there?
| Green marbles |
Black marbles |
Grey marbles |
Total |
| 1 u |
9 u |
10 u |
| |
1 p |
8 p |
|
0.1 =
110 =
110 Fraction of marbles that are black and grey marbles
= 1 -
110 =
910 Total number of marbles = 10 u
10 u = 130
1 u = 130 ÷ 10 = 13
Number of black marbles and grey marbles
= 9 u
= 9 x 13
= 117
Number of black and grey marbles
= 1 p + 8 p
= 9 p
9 p = 117
1 p = 117 ÷ 9 = 13
Number of grey marbles
= 8 p
= 8 x 13
= 104
Answer(s): 104
