Сложение и вычитание дробей с разными знаменателями. Случай 1

1) 3/7 + 16/28 = 12/28 + 16/28 = 28/28 = 1 2) 1/6 + 5/18 = 3/18 + 5/18 = 8/18 = 4/9 3) 5/7 + 3/14 = 10/14 + 3/14 = 13/14 4) 7/15 + 3/5 = 7/15 + 9/15 = 16/15 = 1 1/15 5) 7/15 + 1/3 = 7/15 + 5/15 = 12/15 = 4/5 6) 2/30 + 3/5 = 2/30 + 18/30 = 20/30 = 2/3 7) 2/7 + 4/21 = 6/21 + 4/21 = 10/21 8) 3/5 + 11/20 = 12/20 + 11/20 = 23/20 = 1 3/20 9) 1/5 + 8/15 = 3/15 + 8/15 = 11/15 10) 12/27 + 2/3 = 12/27 + 18/27 = 30/27 = 10/9 = 1 1/9 11) 15/81 + 2/9 = 15/81 + 18/81 = 33/81 = 11/27 12) 7/49 + 1/7 = 1/7 + 1/7 = 2/7 13) 3/2 + 10/16 = 24/16 + 10/16 = 34/16 = 17/8 = 2 1/8 14) 10/64 + 1/8 = 10/64 + 8/64 = 18/64 = 9/32 15) 7/3 + 14/27 = 63/27 + 14/27 = 77/27 = 2 23/27 16) 8/10 + 1/100 = 80/100 + 1/100 = 81/100 17) 11/100 + 1/5 = 11/100 + 20/100 = 31/100 18) 112/4 + 10/100 = 28 + 0.1 = 28.1 19) 1/70 + 4/210 = 3/210 + 4/210 = 7/210 = 1/30 20) 14/30 + 18/150 = 70/150 + 18/150 = 88/150 = 44/75 21) 3/75 + 71/450 = 18/450 + 71/450 = 89/450 22) 4/7 - 16/28 = 16/28 - 16/28 = 0 23) 4/6 - 5/18 = 12/18 - 5/18 = 7/18 24) 2/7 - 3/14 = 4/14 - 3/14 = 1/14 25) 7/15 - 1/5 = 7/15 - 3/15 = 4/15 26) 10/15 - 2/3 = 10/15 - 10/15 = 0 27) 22/9 - 7/3 = 22/9 - 21/9 = 1/9 28) 4/4 - 4/21 = 1 - 4/21 = 17/21 29) 3/5 - 11/20 = 12/20 - 11/20 = 1/20 30) 3/5 - 8/15 = 9/15 - 8/15 = 1/15 31) 21/27 - 2/3 = 21/27 - 18/27 = 3/27 = 1/9 32) 63/81 - 6/9 = 63/81 - 54/81 = 9/81 = 1/9 33) 48/49 - 4/7 = 48/49 - 28/49 = 20/49 34) 10/64 - 1/8 = 10/64 - 8/64 = 2/64 = 1/32 35) 7/3 - 14/27 = 63/27 - 14/27 = 49/27 = 1 22/27 36) 8/10 - 1/100 = 80/100 - 1/100 = 79/100 37) 40/100 - 1/5 = 40/100 - 20/100 = 20/100 = 1/5 38) 112/4 - 10/100 = 28 - 0.1 = 27.9 39) 10/70 - 4/210 = 30/210 - 4/210 = 26/210 = 13/105 40) 13/900 - 7/450 = 13/900 - 14/900 = -1/900