Yellow Tint on existing BMP Image

Question

Using C language, I use this code to tint to grayscale:

    // Compute grayscale value using the formula
    int grayscale = (int)(0.299 * img->pArr[i][j].red +
                      0.587 * img->pArr[i][j].green +
                      0.114 * img->pArr[i][j].blue);
    
    // Set the same grayscale value for each RGB component
    img->pArr[i][j].red = grayscale;
    img->pArr[i][j].green = grayscale;
    img->pArr[i][j].blue = grayscale;

What values should I use to compute a yellow scale for the image?

thanks

I have tried different combinations of decimals with no luck.