x-(31-8)=28, 45+30+x=100​

x-(31-8)=28

x-31+8=28

x=28+31-8

x = 51.

45+30+x=100

x=100-45-30

x = 25

x-(31-8)=28 45+30+x=100

x-23=28 75+x=100

x=28+23 x=100-75

x=51 x=25.