Problem: R varies directly as S​ and inversely as T. When R=34​ and T=149​,S=73​. Find S​ when R=48​ and Tˉ=75​.
Answer Choices:
A. 28
B. 30
C. 40
D. 42
E. 60
Solution:
The relation between R,S, and T can be represented in several ways, to wit,
(1) R=kTS​,k a constant
(2) SRT​=k,k a constant
(3) S1​R1​T1​​=S2​R2​T2​​
Using form 3 we have 73​34​⋅149​​= S2​48​⋅75​​∴ S2​=30