а) (а-b)/3a + (a+b)/3a = (а-b+a+b)/3a = 2a/3a = 2/3
б) (5x-1)/x^2 - (3c-5)/x^2 = (5x-1-3c+5)/x^2 = (5x-3c+4)/x^2
в) (3x+y)/(3x) + (x-2y)/(6x) = (3x+y)/(3x) + (1/2)(x-2y)/3x = (3x+y+1/2x-1/2 y)/3x = (7/2)x - 1/2y)/(3x) = (7/2)x/(3x) - 1/(2*3) = 7/6 - 1/6 = 1
а) (а-b)/3a + (a+b)/3a = (а-b+a+b)/3a = 2a/3a = 2/3
б) (5x-1)/x^2 - (3c-5)/x^2 = (5x-1-3c+5)/x^2 = (5x-3c+4)/x^2
в) (3x+y)/(3x) + (x-2y)/(6x) = (3x+y)/(3x) + (1/2)(x-2y)/3x = (3x+y+1/2x-1/2 y)/3x = (7/2)x - 1/2y)/(3x) = (7/2)x/(3x) - 1/(2*3) = 7/6 - 1/6 = 1