There are 180 marbles in a basket. 0.4 of them are brown marbles, and the rest are grey and red marbles. If there are 15 as many grey marbles as red marbles. How many red marbles are there?
| Brown marbles |
Grey marbles |
Red marbles |
Total |
| 2 u |
3 u |
5 u |
| |
1 p |
5 p |
|
0.4 =
410 =
25 Fraction of marbles that are grey and red marbles
= 1 -
25 =
35 Total number of marbles = 5 u
5 u = 180
1 u = 180 ÷ 5 = 36
Number of grey marbles and red marbles
= 3 u
= 3 x 36
= 108
Number of grey and red marbles
= 1 p + 5 p
= 6 p
6 p = 108
1 p = 108 ÷ 6 = 18
Number of red marbles
= 5 p
= 5 x 18
= 90
Answer(s): 90
