Considering below equation holds

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?

60

V + II - VI = 10
=> I = 10

IV - X + VIII = 20
=> II = 20

IV - VII + VI = 30
=> III = 30

I + II + III = 10 + 20 + 30

Discussion