Return the average of the specified row of the 2D array nums. The rowToAverage parameter is the row that should be averaged. If the rowToAverage does not exist, return -1.0.

Important Note: Copy the following two methods into the window and don't change 
array2DRowAverage.  CodingBat does not allow 2D array parameters, so this method is accepting 
the number of rows, number of columns, and a 1D array.  The first method takes this 
information and creates a 2D array named nums that you will be using. The rowToAverage parameter 
is the row that should be averaged.  Enter your code into method array2DRowAverageB:

public double array2DRowAverage(int rows, int cols, int[] array, int rowToAverage)
{
	int[][] array2D = new int[rows][cols];
	int idx = 0;
	for (int r=0; r<rows; r++)
	{
		for (int c=0; c<cols; c++)
		{
			array2D[r][c] = array[idx];
			idx++;
		}
	}
	return array2DRowAverageB(array2D, rowToAverage);
}

public double array2DRowAverageB(int[][] nums, int rowToAverage) { 

}