Answer:
Good style in solving such problems is to notice/(to observe) immediately from the condition that the difference
between two combinations is the cost of 2 cookies, and it is equal to $9 - $7 = $2. So 2 cookies cost $2.
Then subtracting $2 dollars for 2 cookies from the Greg purchase, you got the cost of two bottles - it is equal to $7 - $2 = $5.
Answer. A bottle of water costs $2.50.
Step-by-step explanation:
