How to find the direct variation when given 2 fractions?

Three people are traveling and need to exchange the currency of their native country for the currency of the country they are visiting. drag each exchange to the category that shows the ratio of currencies in that exchange.

Collin did the work to see if 10 is a solution to the equation r/4=2.4

If you apply the changes below to the linear parent function f(x)=x what is the equation of the new function vertically stretched by a factor of 3 flip over the x axis