Answer :
just like algebra
i lis like x
distribute invisible -1 to second set
-1(-1+3i)=1-3i
now we have
7-9i+1-3i
8-12i
i lis like x
distribute invisible -1 to second set
-1(-1+3i)=1-3i
now we have
7-9i+1-3i
8-12i