Solve M=F*r

$$M = F \cdot r$$

Solve for F

$$\left\{\begin{matrix}F=\frac{M}{r}\text{, }&r\neq 0\\F\in \mathrm{R}\text{, }&M=0\text{ and }r=0\end{matrix}\right.$$

Steps for Solving Linear Equation

Swap sides so that all variable terms are on the left hand side.

$$Fr=M$$

The equation is in standard form.

$$rF=M$$

Divide both sides by r.

$$\frac{rF}{r}=\frac{M}{r}$$

Dividing by r undoes the multiplication by r.

$$F=\frac{M}{r}$$

Solve for M

$$M=Fr$$