Apples at the local farmer's market cost $1.25 per pound.
Write a function rule`f` that gives the total cost of apples in terms of the number of pounds, `x`.
The function rule `f(x)` that gives the total cost of apples in terms of the number of pounds, `x`, can be written as:
f(x) = 1.25 * x
where `x` represents the number of pounds of apples and 1.25 represents the cost per pound.