Question 1119900
m, Man
n, soN


{{{system(m=n+21,m-5=4(n-5))}}}

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{{{n+21-5=4n-20}}} {{{substitution}}}

{{{n+16=4n-20}}}

{{{36=3n}}}

{{{highlight(n=12)}}}
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{{{highlight(m=33)}}}