A, B and C are three positive numbers such that A is 70% of B, and B is 40% of C. If the sum of all three numbers is 336, then 15% of the sum of B and is:

42

70% =  \(\frac{7}{10}\)  &   40% =  \(\frac{2}{5}\)

A   :   B   =   7  :  10    &    B   :   C  =   2  :   5

Overall ,   A   :   B   :  C = 7  :  10  :  25

ATQ,

42R = 336

1R = 8

Now , 15% of B =  \(\frac{3}{20}\) × (10+25) × 8 = 42