А) (2x+y-3) - (y-3+3x) б) (3a+4b+5c)-(a+4b+3c) в) (a-3b+2c)-(-2a-3b-c)​

а) (2x+y-3) - (y-3+3x) = 2x+y-3-y+3-3x = 2x-3x+y-y-3+3 = -x

б) (3a+4b+5c)-(a+4b+3c) = 3a+4b+5c-a-4b-3c = 3a-a+4b-4b+5c-3c = 2c

в) (a-3b+2c)-(-2a-3b-c) = a-3b+2c+2a+3b+c) = а+2а-3b+3b+2c+c = 3a+3c