OpenStudy (anonymous):

Determine the constant of variation for the direct variation given. Type a numerical answer in the space provided. If the number is negative, include the negative in your answer and do not type spaces. R varies directly with S. When S is 16, R is 80.

OpenStudy (paxpolaris):

if Y varies directly with X. $$\implies Y=k \cdot X$$ k is your constant of variation.

OpenStudy (paxpolaris):

in your case: R=k*S ... plug in the given values of R and S and solve for k