Find the sum of all integral values at which the minimum value of the given expression will exist |2x - 5| + |3x -21| + |x + 4|

3 + 4 + 5 + 6 + 7 = 25 Plot values of x on number line, you will get minimum at 2.5 then just trial and error. There are other methods but this felt comparatively easy. Hope it helps :)