[tex]1)~5415+a*2=8965 \\ ~~~~a*2=8965-5415 \\ ~~~~a*2=3550 \\ ~~~~a=3550:2 \\ ~~~~\boxed{a=1775} \\ \\ 2)~a:2+3345=4329 \\ ~~~~a:2=4329-3345 \\ ~~~~a:2=984 \\ ~~~~a=984*2 \\ ~~~~\boxed{a=1968} \\ \\ 3)~8517-a*3=7638 \\ ~~~~a*3=8517-7638 \\ ~~~~a*3=879 \\ ~~~~a=879:3 \\ ~~~~\boxed{a=293}[/tex]
[tex]4)~a:5+6700=6760 \\ ~~~~a:5=6760-6700 \\ ~~~~a:5=60 \\ ~~~~a=60*5 \\ ~~~~\boxed{a=300}[/tex]
