1) 3 15/28 + 6 22/35 2) 4,25 + 1 11/12 - 7/15 3) 7 7/30 - (3 2/15-1 5/12)

1)

3 15/28 + 6 22/35 = 3 75/140 + 6 88/140 =

= (6+3) + (75+88) / 140 = 9 + 163/140 =

= 9 + 1 23/140 = 10 23/140

2)

4,25 + 1 11/12 - 7/15 = 425/100 + 23/12 - 7/15 =

= 17/4 + 23/12 - 7/15 = 255/60 + 115/60 - 28/60=

= 342/60 = 171/30 = 57/10 = 5,7

по действиям:

1) 4,25 + 1 11/12 = 425/100 + 23/12 =

= (425:25) / (100:25) + 23/12 = 17/4 + 23/12 =

= (17*3 + 23) / 12 = 74/12 = 37/6 = 6 1/6

2) 6 1/6 - 7/15 = 37/6 - 7/15 =

= (37*10) / (6*10) - (7*4) / (15*4) =

= (370-28) / 60 = 342/60 = (342:6) / (60:6) = 57/10 = 5,7

3)

7 7/30 - (3 2/15 - 1 5/12) = 7 7/30 - 3 2/15 + 1 5/12 =

= 7 14/60 - 3 8/60 + 1 25/60 = (7-3+1) + (14-8+25) / 60 =

= 5 + 31/60 = 5 31/60

по действиям:

1) 3 2/15 - 1 5/12 = 47/15 - 17/12 = (47*4 - 17*5) / 60 =

= (188-85) / 60 = 103/60 = 1 43/60

2) 7 7/30 - 1 43/60 = 7 14/60 - 1 43/60 = 5 31/60