FIGURE 7.5 Mental Set The equations on the right, expressed in Roman numerals, are obviously incorrect. Your task is to transform each incorrect equation into a correct equation by moving ONE matchstick in each equation. The matchstick can only be moved once. Only Roman numerals and the three arithmetic operators +, –, or = are allowed. Take your best shot at solving the equations before looking at the solutions. Remember, in the Roman numeral system, I = 1; II = 2; III = 3; IV = 4; V = 5.

Source: Research from Duncker (1945).