A careful analysis by the cost accountant of People (Pty) Ltd has determined that; if a plane operates for 1 450 kilometres (km) during a month, the average semi-variable operating costs is R1,50 per km. If the plane operates only 980 km during a month, the average semi-variable operating costs is R1,95 per km. Using the high-low method, the variable costs per km is calculated as: a. R211,50 b. R562 c. R0,56 d. R264