Answer:
10 black marbles
Step-by-step explanation:
Let black marbles be=2x
Then white marbles=5x
Total marbles=7x which in turn is equal to 35. Hence x=5
Black marbles=2*5=10
H2H
Total mass = 6.08 x 10^23 * 1.67 x 10^-24 = 1.01536
The answer is 72
b/c 80% is equal to .80
so you do 90x.80
