Multiple Choice If a company increases the proportion of variable costs relstive to fued costs, its prote will be more stable than is profit based on the existing cost structure. High-low method chooses the highest and lowest levels of activity. If a company increases the proportion of variable costs relative to fined costs in is cost structure, the company will enjoy greater profit when sales increase. Both the High-low method and Least-squares regression method assume that costs are linear. The slope of proft graph is determined by unit contribution margin