There are 180 marbles in a box. 0.3 of them are yellow marbles, and the rest are pink and black marbles. If there are 34 as many pink marbles as black marbles. How many black marbles are there?
| Yellow marbles |
Pink marbles |
Black marbles |
Total |
| 3 u |
7 u |
10 u |
| |
3 p |
4 p |
|
0.3 =
310 =
310 Fraction of marbles that are pink and black marbles
= 1 -
310 =
710 Total number of marbles = 10 u
10 u = 180
1 u = 180 ÷ 10 = 18
Number of pink marbles and black marbles
= 7 u
= 7 x 18
= 126
Number of pink and black marbles
= 3 p + 4 p
= 7 p
7 p = 126
1 p = 126 ÷ 7 = 18
Number of black marbles
= 4 p
= 4 x 18
= 72
Answer(s): 72
