Meha is helping her aunt to plan a birthday party for her cousin at the science center. Her aunt tells her that the party will cost $150, plus $10.50 per child and $5.50 per adult. There needs to be at least one adult and at least one child at the party. She has budgeted $300 for the party and that is the maximum amount she wants to spend

To determine how many children and adults can attend the party while staying within the budget of $300, let's set up an equation based on the given costs. Let \( x \) be the number of children, and \( y \) be the number of adults attending the party. The total cost of the party can be represented by the equation:

\[ 150 + 10.50x + 5.50y = 300 \]

First, let's simplify the equation by subtracting the flat fee of $150 from both sides to find out how much is left for paying per person:

\[ 10.50x + 5.50y = 300 - 150 \]
\[ 10.50x + 5.50y = 150 \]

Let's simplify this equation by dividing all terms by 5.50 to make it easier to solve:

\[ \frac{10.50x}{5.50} + \frac{5.50y}{5.50} = \frac{150}{5.50} \]
\[ 1.909x + y = 27.273 \]

Now we need to manipulate the equation to solve for either \( x \) or \( y \). Let's solve for \( y \):

\[ y = 27.273 - 1.909x \]

Since \( y \) has to be a whole number because you can't have a fraction of an adult attending, and there must be at least one adult, we will need to choose values of \( x \) (the number of children) that result in \( y \) being a whole number equal to or greater than 1.

Let's try different values for \( x \) to see which ones would work:

With 1 child (\( x = 1 \)):
\[ y = 27.273 - 1.909 \cdot 1 \]
\[ y = 27.273 - 1.909 \]
\[ y \approx 25.364 \]

With 2 children (\( x = 2 \)):
\[ y = 27.273 - 1.909 \cdot 2 \]
\[ y = 27.273 - 3.818 \]
\[ y \approx 23.455 \]

We can continue this pattern until we reach a combination that goes over budget. However, we need to remember that the $300 budget is the maximum amount to spend, so the actual combination of children and adults must result in a total cost that does not exceed $300.

Each whole number of adults reduces the total sum available for children because each adult is $5.50 cheaper than a child. To maximize the number of children, the number of adults should be kept to a minimum, but we have to ensure we meet the condition of at least one adult.

Let's try \( x = 10 \) (just as an example):

\[ y = 27.273 - 1.909 \cdot 10 \]
\[ y = 27.273 - 19.090 \]
\[ y \approx 8.183 \]

Since we're looking for whole numbers, let's round \( y \) down to keep the total cost within the budget:

\[ y = 8 \]

Now let's calculate the cost with this combination:

\[ Total cost = 150 + 10.50 \cdot 10 + 5.50 \cdot 8 \]
\[ Total cost = 150 + 105 + 44 \]
\[ Total cost = 299 \]

With 10 children and 8 adults, the cost would be $299, which is just under the budget. Now, remember that we rounded \( y \) down. The calculation won't be exact for other values of \( x \) without rounding. The key is to find how many children can be included, with at least one adult, while staying under the $300 budget by using trial and error or an automated method to systematically check for valid pairs of \( x \) and \( y \).