Question 1096052
?

{{{system(t+u=9,t-u=7)}}}


2t=16
t=8
and
u=1

number,{{{highlight(81)}}}


{{{system(t+u=9,-t+u=7)}}}

{{{2u=18}}}
{{{u=8}}}
and
{{{t=1}}}

number, {{{highlight(18)}}}


Either of those will work according to the description.