If a : b = 3 : 5 and a = 24, then what is the value of b?  Ops:   A. 40    B. 35    C. 30    D. 45

The given ratio is a : b = 3 : 5.

This means that 'a' is 3 parts of a whole and 'b' is 5 parts of the same whole.

We are also given that a = 24.

To find the value of 1 part, we divide the value of 'a' by the number of parts it represents. So, 1 part = a/3 = 24/3 = 8.

Now, to find the value of 'b', we multiply the value of 1 part by the number of parts 'b' represents. So, b = 5 parts * 8 = 40.

Therefore, the value of 'b' is 40. So, the answer is A. 40.