Вычислите: а) 1/6+2/3 б) -1/3+2/7 b) -4/9+5/6

A) 1/6+2/3 = 1/6+4/6 = 5/6
б) -1/3+2/7 = -7/21 + 6/21 = -1/21
в) -4/9+5/6= -8/18+15/18 = -7/18

А) 1/6 + 2/3 = 1/6 + (2*2)/6= 1/6 + 4/6 = 5/6
б) -1/3 + 2/7 = (2*3)/21 - (1*7)/21= 6/21 - 7/21 = - 1/21
в) -4/9 + 5/6 = (5*3)/18 - (4*2)/18 = 15/18 - 8/18 = 7/18