A factory saved a total of 140 tons of water in the first 4 days of early March, and an average of 32.5 tons of water per day in the last 6 days. How many tons of water was saved on average every day in early March?
某厂三月上旬前4天共节约用水140吨，后6天平均每天节约用水32.5吨．这个三月上旬平均每天节约用水多少吨？
<result>3.3</result>