You can only move one of the lines to make the equation correct ? - [ III - IV = VII ]

Question

Considering below equation holds

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

Then, I + II + III = ?

Answer 1

Move one of two lines of equal sign to the top of minus sign
III=IV-VII (read from right to left)