а) 2a/(a+2) + (2-a)/(a+2)
= (2a + 2 - a)/(a+2)
= (a+2)/(a+2)
= 1

б) (3x+2)/(2x-1) + (x-1)/(1-2x)
= [ (3x+2)(1-2x) + (x-1)(2x-1) ] / (2x-1)(1-2x)
= [ 3x - 6x^2 + 2 - 4x + 2x - 1 ] / (-2x + 1)(2x - 1)
= (-6x^2 + x + 1) / (-2x + 1)(2x - 1)