1. Simultaneous Equations

2. Renzo buys a round of drinks at a local restaurant. He buys two cocktailsand three cappuccinos for his four friends He pays 420 Baht for all the drinks.

3. The next round is bought by Rafael. He buys three cocktails He pays 480 Baht. and two cappuccinos.

4. How does she work out the cost of each? Andrea wants to buy the next round but before she does she wants to know how much is each cocktail and each cappuccino.

5. César says this is easy! If we let each cocktail be x and each cappuccino be y. Then for …

6. Renzo ’ s round we have 2 cocktails (2x) and 3 cappuccinos (3y) The total cost is 420 Baht

7. and for …

8. Rafael ’ s round we have 3 cocktails (3x) and 2 cappuccinos (2y) The total cost is 480 Baht

9. To find the cost of each we must solve both equations simultaneously to find the value of x and y

10. Subtract 4 from 3 Divide by 5 Now substitute into 1 Subtract 180 Divide by 2

11. So César says that each cocktail costs 120 Baht and each cappuccino costs 60 Baht.