Question

Suppose d varies directly as f, and d varies inversely as g. Find g when d = 6 and f = -7, if g = 12 when d = 9 and f = 3.

Answer 1

`\qquad \qquad \textit{combined proportional variation} \\\\ \begin{array}{llll} \textit{\underline{y} varies directly with \underline{x}}\\ \textit{and inversely with }\underline{z^5} \end{array} ~\hspace{6em} \stackrel{\textit{constant of variation}}{y=\cfrac{\stackrel{\downarrow }{k}x}{z^5}~\hfill } \\\\[-0.35em] ~\dotfill`

`\begin{array}{llll} \textit{`