Answer:
-6 a b + b + a
Explanation:
Simplify the following: 
 
-(a - b + a b) - a b - 4 a b + 2 b - 2 b + 3 a - a 
 
Hint: | Group like terms in 3 a - 2 b - a b - (a b - b + a) - 4 a b + 2 b - a. 
 
Grouping like terms, 3 a - 2 b - a b - (a b - b + a) - 4 a b + 2 b - a = -(a b - b + a) + (-a b - 4 a b) + (3 a - a) + (2 b - 2 b): 
 
-(a b - b + a) + (-a b - 4 a b) + (3 a - a) + (2 b - 2 b) 
 
Hint: | Combine like terms in -a b - 4 a b. 
 
a b (-1) + a b (-4) = -5 a b: 
 
-(a b - b + a) + -5 a b + (3 a - a) + (2 b - 2 b) 
 
Hint: | Combine like terms in 3 a - a. 
 
3 a - a = 2 a: 
 
-(a b - b + a) - 5 a b + 2 a + (2 b - 2 b) 
 
Hint: | Look for the difference of two identical terms. 
 
2 b - 2 b = 0: 
 
-(a b - b + a) - 5 a b + 2 a 
 
Hint: | Distribute -1 over a b - b + a. 
 
-(a b - b + a) = -a b + b - a: 
 
-a b + b - a - 5 a b + 2 a 
 
Hint: | Group like terms in -a b - 5 a b + b + 2 a - a. 
 
Grouping like terms, -a b - 5 a b + b + 2 a - a = (-a b - 5 a b) + b + (-a + 2 a): 
 
(-a b - 5 a b) + b + (-a + 2 a) 
 
Hint: | Combine like terms in -a b - 5 a b. 
 
a b (-1) + a b (-5) = -6 a b: 
 
-6 a b + b + (2 a - a) 
 
Hint: | Combine like terms in 2 a - a. 
 
2 a - a = a: 
 
Answer: -6 a b + b + a