Subtract km from both sides of the equation.
Factor m out of 660m-km.
Factor m out of 660m.
Factor m out of -km.
Factor m out of m⋅660+m(-k).
Divide each term by 660-k and simplify.
Divide each term in m(660-k)=0 by 660-k.
Cancel the common factor of 660-k.
Cancel the common factor.
Divide m by 1.
Divide 0 by 660-k.
Solve for m 660m=km