Mia buys 3 gallons of gas that cost d dollars per gallon. bob buys g gallons of gas that cost 3 per gallon. write an expression for the amount of gas for mia? write an expression for the amount of gas for bob? what do the numerical and the variable represent in each expression?

3(d) and 3 (g)
d represents the price. so you multiply 3 by however much the has cost.
g represents the gallons and 3 represents the cost and again you multiply

Mia buys 3 gallons of gas at d, or 3 * d = 3d.
The number 3 represents the quantity(how many) gallons she bought
The variable d represents the rate at which Mia bought the gas.

Bob buys g gallons at 3, or 3 * g = 3g.
The variable g number 3 represents the quantity(how many) gallons he bought
The number 3 represents the rate at which Mia bought the gas.