Concept: The question tests on the basics of equation.

Solution:

 
5b= 6c= 7d= 120 (Given)

=> b = 120/5 = 24

c=120/6=20

& d=120/7

Thus, 7(b)(d) / c

=7*(24)*(120) / (20)* 7

= 143.64 (Approx. 144) (option c).