In a proportion a:b :: c:d, a*d = b*c. So, 4 * 13.5 = x * 9 => 54 = 9x => x = 6.
समानुपात a:b :: c:d में, a*d = b*c होता है। इसलिए, 4 * 13.5 = x * 9 => 54 = 9x => x = 6।