Two-fifth of one-third of three-seventh of a number is 15. What is 40% of that number?

A. 72
B. 84
C. 136
D. 140
E. None of these
Explanation:
Let the number be x. Then,
2/5 of 1/3 of 3/7 of
x = 15 => x = (15 * 5/3 * 3 * 5/2) = 525/2
40% of 525/2 = (40/100 * 525/2) = 105