Please explain supply and demand

In July, gasoline prices were well over $4 per gallon. Today, the price is below $1.62 per gallon. They tell us it was supply and demand. Food prices have skyrocketed 30 percent or more since we began adding fuel delivery charges, etc. I hope someone can explain this supply and demand, as I can't buy that as I am eating the same, and everyone I know isn't eating less.

Nick Schiavone

Bloomingdale