7*(a-1)+2*(a+1)=30 плз

Question

7*(a-1)+2*(a+1)=30 плз

Answer 1

7a-7+2a+2=30
9a=35
a=3,(8)

Answer 2

7(а-1)+2(а+1)=30
7а-7+2а+2=30
7а+2а=30+7-2
9а=35
а=35:9
а=35/9