Question

Y varies directly as x If x = 5 when y = 12. Write an equation that relates x and y. Then find x when y = 36

Answer 1

`\begin{gathered} y\text{ varies directly as x means that} \\ y=mx \\ \text{where m is a constant of proportionality.} \\ We\text{ know that when x=5, y =12, hence} \\ 12=m(5) \\ m=(12)/(5) \\ \text{Therefore, the euqtion searched is} \\ y=(12)/(5)x \\ \text{Now, we must find x when y=36. Then} \\ 36=(12)/(5)x \\ (36)/(12)=(x)/(5) \\ 3=(x)/(5) \\ 3\cdot5=x \\ x=15 \end{gathered}`