Since x ∝ y, x = ky. 12 = k(4) => k = 3. Now, for y = 15, x = 3(15) = 45.
चूंकि x ∝ y, x = ky। 12 = k(4) => k = 3। अब, y = 15 के लिए, x = 3(15) = 45।