All functions have an inverse expression.
- The cost function is:
. - The inverse function is:

From the question, we have the following observations:
- Base fare = 50000 pesos for first 100
- Additional guest = 100 pesos
So, the cost function would be:

Where: x represents the number of guests, and C(x) represents the cost function
Expand

Evaluate like terms

To calculate the inverse function, we have:

Replace C(x) with y

Swap x and y

Subtract 40000 from both sides

Divide both sides by 100

Rewrite as:

Split


Hence, the inverse function is: 
Read more about functions and inverse at:
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