Answer:

Explanation:
Given : A jar contains 75 marbles.
 2/5 of the marbles are black.
To Find : What fraction of the marbles are black, using 75 as the denominator
Solution:
Total marbles = 75
 2/5 of the marbles are black.
No. of black marbles = 

 = 

So, fraction of the marbles are black, using 75 as the denominator = 
