A.2.1.1 Opener - A Main Dish and Some Side Dishes

Here are some letters and what they represent. All costs are in dollars.

• m represents the cost of a main dish.
• n represents the number of side dishes.
• s represents the cost of a side dish.
• t represents the total cost of a meal.

Here are some questions to think about: What is an equation? What does it tell us?

Can equations contain only numbers?

Could this equation be true: m + 5 = t? How do you know?

When might the equation m + 5 = t be false?

One equation tells us that a main dish is $7.50. Another equation tells us that it is equal to the expression s + 7.50. Could both be true? Are they both appropriate for expressing the cost of a main dish?