Question 937865
Symbolism suggests Arithmetic Sequence, with {{{a[1]}}} as the first term,  a common difference d, and general term {{{a[n]=a[1]+(n-1)d}}}.



Use the formula to rewrite your given equations.


{{{a[1]+(7-1)d=7}}}  and  {{{a[1]+(3-2)d+a[1]+(9-1)d=82}}}.


Simplify and solve the system.