Question 1051936
The task can be understood, undo everything that was done to M.  You example shows {{{M^2}}}, so to undo this, you will use the inverse operation {{{X^(1/2)}}} for whatever is X.


{{{(2M^2)(N^3)(L^4)=10c}}}


{{{2M^2=(10c)(N^-3)(L^-4)}}}


{{{2M^2=(10c)/(N^3*L^4)}}}


{{{M^2=(5c)/(N^3*L^4)}}}


{{{(M^2)^(1/2)=((5c)/(N^3*L^4))^(1/2)}}}


{{{M=((5c)^(1/2))/(N*L*N^(1/2))}}}------for which you might still want to rationalize the denominator, or also use square-root notation instead of rational power notation.
(NOTE: Display Rendering not working too neatly)