Since your

`Calculate`

method is non-static, it has an instance to work with: the current instance (which is also known as `this`

- but in this example you don't need to use it explicitly).For example, if I create a Fraction class:

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public class Fraction { public int Numerator; public int Denominator; public Fraction (int numerator, int denominator) { Numerator = numerator; Denominator = denominator; } }I can add a method to evaluate the fraction as a decimal value:

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public double Evaluate() { return (double) Numerator / (double) Demoninator; }

This uses the values that were set when the class instance was created.

Your code can do the same: set the class instance values directly when you call your method:

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public MonthlyPayment alculate(int i) { Month = i; InitialBalance =10.000f ; Interest = ((9.75 /100) / 12) * InitialBalance; double v = 1 + x.Interest; ... return this; }