1. Write a function to find the nth fibonacci number in the fibonacci sequence*In the Fibonacci sequence, the first two numbers are 0 and 1 and each number after that is the sum of the previous two numbers in the sequence. So, the sequence looks like this: 0, 1, 1, 2, 3, 5, 8, 13, 21… and so on. The “0” in the sequence is considered to be the 0th element, the first “1” is considered to be the 1st element, the 2 is the 3rd element, etc. And the problem specifically states that the function or method needs to return the nth element in the Fibonacci sequence, where the input to that function or method is n.function GetFibonacci ($n)

    {

    //Insert your solution here

    }

  2. Write a function that will return the list of duplicate numbers in an array of 100 numbers. Your solution should return a list of only those numbers that appear more than once in the provided array.{//insert your solution here

    }

  3. Given 3 int values, a b c, return their sum. However, if one of the values is 13 then it does not count towards the sum and values to its right do not count. So for example, if b is 13, then both b and c do not count.luckySum(1, 2, 3) → 6luckySum(1, 2, 13) → 3

    luckySum(1, 13, 3) → 1

    Write a function to return the lucky sum of three given numbers

    function luckySum($a, $b, $c)

    {

    //please enter solution here.

    }