Question 1087456
{{{M=14+J}}}
{{{MJ=51}}}
Substituting,
{{{(14+J)J=51}}}
{{{J^2+14J-51=0}}}
{{{(J-3)(J+17)=0}}}
Only positive solutions make sense here,
{{{J-3=0}}}
{{{J=3}}}
Now use either equation to solve for M.