Question

(a-b) - [ -3a - [b+2(-2a+b-(a-b)] + 2a - 2(-2a+b)] - (a-b) + a]

Answer 1

(a-b) - [-3a -[b + 2(-2a+b-(a-b))+2a -2(-2a+b)] -(a-b) +a] =
 a-b -[-3a -[b +2(-2a+b-a+b)+ 2a +4a-2b] -a+b+a]=
 a-b -[-3a -[b -4a +2b-2a+2b+2a+4a-2b]-a+b+a] =
 a-b -[-3a -b+4a-2b+2a-2b-2a-4a+2b] -a +b +a =
 a -b +3a +b -4a +2b -2a +2b +2a +4a -2b -a +b +a = reduces terminos semejantes te queda     4a + 3b

espero te ayude