Alicia runs a small business mowing yards in the summer. for every yard she mows, she earns $40. however, she spends part of this money on gasoline for her lawnmower. each gallon of gasoline costs $3. write an expression for the amount of money that alicia earns in a day, where y is the number of yards she mows and g is the number of gallons of gasoline she buys.
What is an expression?