The cost for children under twelve at a certain buffet restaurant is a base charge of a dollar plus twenty-five cents for each year of the child's age. Represent this cost as an expression, using y to stand for the child's age in years. Then use the expression to find the cost for a child who is nine.

Step-by-step explanation:

Given

of child's age

Solving (1):

Determine the cost function.

Represent the years as y.

So, we have:

* y

Convert 25 cents to dollars.

So, we have:

The cost amount is then:

--- This is the cost function

Solving (b): Cost of 9 years old.

In this case;

Substitute 9 for y in

--- This is the cost for a child of 9