(i) If we substitute x = 4, we get L.H.S = x + 4 = 4 + 4 = 8 and R.H.S = 2x = 2 x 4 = 8 ∴ L.H.S = R.H.S. Hence, 4 is a solution of x + 4 = 2x. (ii) If we substitute y = 3, we get L.H.S = y - 7 = 3 - 7 = 4 and R.H.S = 3(3) + 8 = 9 + 8 = 17 ∴ L.H.S ≠ R.H.S. Hence, 3 is not a solution of y - 7 = 3y + 8 (iii) If we substitute u = 5, we get L.H.S = 3u + 2 = 3(5) + 2 = 15 + 2 = 17 and R.H.S = 2u + 7 = 2(5) + 7 = 10 + 7 = 17 ∴ L.H.S = R.H.S. Hence , 5 is a solution of 3u + 2 = 2u + 7