4. J Company uses the high-low method of estimating costs. Ajax had total costs of $50,000 at its lowest level of activity, when 5,000 units were sold. When, at its highest level of activity, sales equaled 12,000 units, total costs were $78,000. What would Ajax estimate its total cost to be if sales equaled 8,000 units? a) $32,000 b) $52,000 c) $62,000 d) $80,000