Найдите сумму или разность 1) а) 1/3+5/6 б) 5/7+1/14 2) 3/11+1/13 б) 7/20+2/3 3) 5/34-41/51 б) 3 целых 1/30-5 целых 7/90

1) а) 1/3 + 5/6 = 2 * 1/2 * 6 + 5/6 = 2/6 + 5/6 = 7/6 = 1 1/6;

б) 5/7 + 1/14 = 2 * 5/2 * 7 + 1/14 = 10/14 + 1/14 = 11/14.

2) 3/11 + 1/13 = 3 * 13/11 * 13 + 1 * 11/13 * 11 = 39/143 + 11/143 = 50/143.

б) 7/20 + 2/3 = 7 * 3/20 * 3 + 2 * 20/3 * 20 = 21/60 + 40/60 = 61/60 = 1 1/60.

3) 5/34 - 41/51 = 5 * 3/34 * 3 - 41 * 2/51 * 2 = 15/102 - 82/102 = - 67/102.

б) 3 1/30 - 5 7/90 = 3 * 30 + 1/30 - 5 * 90 + 7/90 = 91/30 - 457/90 = 91 * 3/30 * 3 - 457/90 = 273/90 - 457/90  = - 184/90 = - 2 4/90.