A certain quantity is measured on two different scales, the R-scale and the S-scale, that are related linearly. Measurements on the R-scale of 6 and 24 correspond to measurements on the S-scale of 30 and 60, respectively. What measurement on the R-scale corresponds to a measurement of 100 on the S-scale?
Choose the correct choice from the following answers.
A) 20  B) 36  C) 48  D) 60  E) 84

Rationale: question says they are both related linearly so they the relationships can be represented by standard linear definition y = mx + b . let s scale = y . and r scale = x . 30 = 6 m + b eqn 1 60 = 24 m + b eqn 2 eqn 2 - eqn 1 = > 30 = 18 m = > m = 5 / 3 solving for b using either equation gives us b = 20 linear relationship is represented by y = ( 5 / 3 ) x + 20 solve for 100 : 100 = 5 / 3 x + 20 80 = 5 / 3 x x = 48 ans = c
Answer: C