-25,7= -25 7/10
-25 7/10 + (-13 3/4)= -25 7/10 - 13 3/4= - 25*10+7/10 - 13*4+3/4= -257/10 - 55/4=
= - 2*257/2*10 - 5*55/5*4= -514/20 - 275/20= -514-275/20= -789/20= -39 9/20
2) -6,5= -6 5*10= -6 1/2
- 17 1/2 + (-6 1/2)= -17 1/2 - 6 1/2= - 17*2+1/2 - 6*2+1/2= - 35/2 - 13/2= -35-13/2= -48/2= -24
3) -8,8= - 8 8/10= -8 4/5
-8 4/5 + (-13 5/7)= -8 4/5 - 13 5/7= - 8*5+4/5 - 13*7+5/7= -44/5 - 96/7= -7*44/7*5 - 5*96/5*7=
- 308/35 - 480/35= -308-480/35= 788/35= - 22 18/35
4) -2 4/15+(-4 7/12)= -02 4/15 - 4 7/12= - 2*5+4/15 - 4*12+7/12=- 34/15 - 55/12= - 4*34/4*15 - 5*55/5*12= - 136/60 - 275/60= - 136 - 275/60= - 411/60= 137*3/20*3= - 137/20= 6 17/20
5)- 6,25= - 6 25/100= - 6 1/4
- 6 1/4 +( -15 1/4)= - 6 1/4 - 15 1/4= - 6*4+1/4 - 15*4+1/4= -25/4 - 61/4= -25-61/4 =-86/4= -43*2/2*2= -43/2= - 21 1/2
6) -0,09= - 9/100
- 8,2= -8 2/10= - 8 1/5
- 9/100+(-8 1/5)= - 9/100 - 8 1/5= - 9/100 - 8*5+1/5= 9/100 - 41/5= -1*9/1*100 - 20*41/20*5= -9*/100 - 820/100= -9-820/100= -829/100= - 8 29/100