Verified answer

1)

19-17=2

19-(-17)=19+17=36

19-8,5=11,5

19-(-4/9)=19+4/9=19 4/9

19-30,2= - 11,2

2)

5+4*3=5+12=17

5+4*(-7)=5-28= - 23

5+4*0,25=5+4 * 1/4=5+1=6

5+4*(-4/3)=5 - 16/3=5 - 5 1/3= - 1/3

5+4 * (-1/42)=5 - 2/21=4 19/21