If a, b, c, x are in proportion, then a/b = c/x. So, 4/9 = 12/x => 4x = 108 => x = 27.
यदि a, b, c, x समानुपात में हैं, तो a/b = c/x। इसलिए, 4/9 = 12/x => 4x = 108 => x = 27।