Suppose p varies directly as the cube of x, and inversely with y. If p=5/8 when x=4 and y=10, find p when x=2 and y=16
How do you set up the steps?
When P varies directly with x, it means, $\displaystyle p=k_1x$ for some constant k.
If P varies directly with the cube of x then, $\displaystyle P = k_1 x^3$
When P varies inversely with y it means, $\displaystyle P = \frac{k_2}{y}$
Now if you use the initial conditions provided you should be able to solve for the constants $\displaystyle k_1 \mbox{ and } k_2$