Question

(a-1)-(a-2)+(a-3)= ?

Answer 1

(a-1)-1(a-2)+(a-3)=a-1-a+2+a-3=a-2
The answer is a-2

Answer 2

First of all you need to get rid of parenthesis:

`(a-1)-(a-2)+(a-3)=a-1-a+2+a-3`

Then sum members of expression:

`a-1-a+2+a-3=(a - a + a) + (2 - 1 - 3)=a-2`

So,
`(a-1)-(a-2)+(a-3)=a-2`