[tex]\overline{12a}+\overline{3a4}+\overline{a56}=813\\120+a+304+10\cdot a+100\cdot a+56=813\\480+111\cdot a=813\\111\cdot a=333\\a=333:111\\\boxed{a=3}\\\text{La celalalt exercitiu nu ai scris toata cerinta, dar e acelasi model ca ex. asta }[/tex]
