1)(0,6)/(1+1^1/2)= (0.6)/(1+1)=0.6/2=0.3
2)(1)/( (1/72)- (1/99) ) = (1)/((11-8)/792) =(1)/((3)/792)= (1)/(1/264)=264
3)12*(1/6)^2-20* (1/6)= 12* (1/36)-10* (1/3)= (1/3)-(10/3)=-9/3=-3
4)( (3/20) + (7/30) )*15= ( (9+14)/60 ) *15 = (23/60)*15= 23/4=5 4/3
5)0.8*(-10^4)+3*(-10)^3+78= 0.8*10^4+3*(-10)+78=0.8*10000-3*1000+78=8000-3000+78= 5078