1)3/8×(-4)+5=3/8×(-4/1)+5/1=-3/2+5/1=-3+10/2=7/2=3,5
2)5/9÷(-1/3)-7=5/9÷(-1/3)-7/1=5/9×(-3/1)-7/1=-5/3-7/1=-5-21/3=-26/3=-8 2/3
3)2/5×(-3)-4/5=2/5×(-3/1)-4/5=-6/5-4/5=-10/5=-2
4)5/12÷1/4-(-1/3)=5/12×4/1+1/3=5/3+1/3=6/3=2
5)1/2×(-4)-5=0,5×(-4)-5=-2-5=-7
6)4/9÷(-2/3)+1=4/9×3/2+1/1=-2/3+1/1=-2+3/3=1/3