16) Two customers went to a restaurant to buy drinks and tacos. Each drink ordered cost the same amount
and each taco they ordered cost the same amount.
● The first customer paid $21.12 for 3 drinks and 6 tacos.
● The second customer paid $30.91 for 4 drinks and 9 tacos.
What is the cost of each drink if x represents the price of each drink and y represents the price of each taco?