1) 4 x - 5 x + 8 x - 11 x - 20 x = - 24 x
= - x + 8 x - 31 x =
= 7 x - 31 x =
= - 24 x
2)
3 x - ( x + 4 x ) + 12 x - 15 x = - 5 x
= 3 x - 5 x - 3 x =
= - 5 x
3).
12 y + ( 4 y - 7 y ) - ( 2 y ) = 7 y
= 12 y - 3 y - 2 y =
= 9 y - 2 y =
= 7 y
4).
( 22 a - 30 a ) + (18 a - 20 a ) + 10 a = 0
= - 8 a - 2 a + 10 a =
= - 10 a + 10 a =
= 0