Zredukuj wyrazy podobne

( a+ b) - ( 2a + b ) - ( a- 2b) =
2( x+ 1) - 3( x- 1) =
2x(5 + 3x) - 4x(7+3x) =
(x+ 3)( 2x -7)=
15x + 20y /5 - 4x + 8y/ 2 =