Trouble with calling method [duplicate]

Answer 1

You're doing int division which always returns an int. For example 5/9 returns 0.

Instead use double division 5.0/9.0

For your code:

public static double celsius (double fahrenheit) {
    return (fahrenheit - 32) / (5.0 / 9.0);
}

We should probably close this question as a duplicate as it's been asked many many times. For example: fahrenheit-to-celsius-conversion-yields-only-0-0-and-0-0

Answer 2

(5/9) is an integer division, it always returns 0.

It should be: (5.0/9.0)