You have the following expression for the cost of three different type of pizzas, x, y and z.
[tex]10x+12y+14z[/tex]If the previous expressions determines the cost of the pizzas in dollars, due to buy certain number of x pizzas, y pizzas and z pizzas, then, the coefficients means the cost in dollars for each type of pizza. Hence, each x pizza costs 10 dollars, each y pizza costs 12 dollars and each z pizza costs 14 dollars.
