4.
5/6 + 1/4=10/12 + 3/12=13/12=1 1/12
7/8 - 5/6=21/24 - 20/24=1/24
3/10 - 4/15=9/30 - 8/30=1/30
5 - 3 2/7=4 7/7 - 3 2/7=1 5/7
4/9 * 3/8=1/6
5/8 : 9/10=5/8 * 10/9=25/36
2 6/7 : 1 3/7=20/7 : 10/7=20/7 * 7/10=2
6 3/5 * 10=6*10 + 3/5*10=60 + 30/5=60+6=66
.
5.
4,2-8= - 8+4,2= - (8-4,2)= - 3,8
- 2,4+5,6=5,6 - 2,4=4,2
-2,1 - 3,2= - (2,1+3,2)= - 5,3
1,2 * (-5)= - 1,2*5= - 6
-8 * 4,5= - 36
-0,9 * (-0,1)=0,9*0,1=0,09
38:(-0,19)= - 3800:19= - 200
-16:0,2= - 80
-6,4:(-8)=6,4:8=0,8
.
6.
6 1/3 - 8= - 8+6 1/3= - (8 - 6 1/3)= - 1 2/3
-2 2/7 + 4 3/5=4 3/5 - 2 2/7=4 21/35 - 2 10/35=2 11/35
5 1/3 - 6 1/4=5 4/12 - 6 3/12= - (6 3/12 - 5 4/12)= - (5 15/12 - 5 4/12)= - 11/12
3/8 : (-9/16)= - 3/8 * 16/9= - 2/3
5/12 * (-6)= - 30/12= - 5/2= - 2 1/2
- 3 2/9 * 3= - (3*3 + 2/9 * 3)= - (9+2/3)= - 9 2/3
4/7 * (-49)= - 4*7= - 28
-16 : (- 4/9)=16 * 9/4=4*9=36
-3 1/2 * (-1 3/7)=7/2 * 10/7=5