Solving word problems in cost comparisons using oil prices.
Fuel oil prices averaged $0.93375 in the winter of 1998, then shot up to $1.02 in
winter 1999. Calculate the additional fuel costs for a household that used 863 5/8
gallons of fuel oil during the winter of 1999.
...f $0.93375 and $1.02 namely: 0.08625, let's call this quantity ...