<u>Answer:</u>
$6.00
<u>Step-by-step explanation:</u>
To solve this problem, we have to construct two separate equations for each family, and then use any of the methods for solving simultaneous equations.
Let's consider <em>h </em>to represent the cost of 1 hot dog, and <em>w </em>to mean the cost of 1 water bottle.
• For the first family:

We can rearrange the equation to make <em>w</em> the subject:
⇒ 
⇒ 
• For the second family:

Since we have previously obtained an expression for <em>w</em> in terms of <em>h</em>, we can substitute that expression for <em>w</em> in the above equation, and then solve for <em>h</em>:
⇒ 
⇒ 
⇒
[Multiplying both sides of the equation by 3]
⇒ 
⇒ 
⇒ 
∴ The price of one hot dog is $6.00.