For example, (x +1)*(x +1) is a term built from the constant 1, the variable x, and the binary function symbols + and *; it is part of the atomic formula (x +1)*(x +1) â¥ 0 which evaluates to true for each real-numbered value of x.
In recent weeks, the U.S. diesel fuel price has been hovering around $4.16 per gallon. LNG is selling for about $2.92 per diesel gallon equivalent, 30 percent less, according to Clean Energy Fuels' current price report, which is updated weekly.
1 March prices averaged $3.695 per gallon in 2013, $3.829 per gallon in 2012, $3.533 per gallon in 2011 and $2.778 per gallon in 2010.  Average gas prices have increased 49 out of 52 days for a total of 29 cents per gallon.