public static int mystery(int value)
{
    if(value <= 10)
        return value * 3;
    
    return value + mystery(mystery(value / 5)); // finished call 1
    //              call2     call 1               got back 9
                                                // stops at call 2 and calls m(9)
}

Call stack

m(9)
m(3)   returns 9
m(15)2    15 + ____
m(5)   returns 15
m(27)2    27 + ____
m(9)   returns 27
m(45)2    45 + ____

Forward to Step 11
Back to Step 9
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