1) 1/3а-б при а=12, б=2/3
1/3• 12 - 2/3= 12/3- 2/3= 10/3= 3 1/3
2)м-2н при м=-5, н=1/2
(-5)-2•1/2= (-5)- 2/2= (-5)- 1= -(5+1)=-6
3) х+5:у при х=-4,2 у=2
(-4,2)+ 5:2= (-4,2)+ 2,5= -(4,2-2,5)= -1,7
4)х-3:у при х=-1/6 у=2,3
(-1/6)- 3:2,3= (-1/6) - 3: 23/10= (-1/6)- 3•10/23= (-1/6)- 30/23= - (1/6+ 30/23)=
-(1/6+ 1 7/23)=
- ( (1•23)/(6•23)+ 1 (7•6)/(23•6))=
- (23/138+ 1 42/138)= - (1 65/138).