Match each equation with the way in which $r$ varies with respect to $t$ in that equation.
IMPORTANT!! You only have 3 attempts to get this problem right!

1. $\displaystyle \frac{3r}{t^3}=v^2s$

2. $\displaystyle \frac{v}{27t}=\frac{4}{s^2r^3}$

3. $\displaystyle 4rt=\frac{ks^2}{v^3}$

4. $\displaystyle 18=\frac{4r^2}{v^3s^2t}$

5. $\displaystyle \frac{1}{5r^2t}=\frac{1}{5s^2v}$

6. $\displaystyle \frac{st^2}{8r}=2vs$

A. directly with the cube root of $t$
B. inversely with the square root of $t$
C. inversely with $t$
D. directly with the square root of $t$
E. directly with the cube of $t$
F. directly with the square of $t$