According to a restaurant company's 2005 annual report, the cost of sales increased from $2.9 billion in 2001 to $3.9 billion in 2005. During the same time period, revenue from sales increased from $3.8 billion to $5.1 billion. Answer the following questions using mathematical computations to substantiate your results.
(a) Between 2001 and 2005, was the cost of sales increasing more rapidly than the revenue from sales? Explain.