If 3(x - y) = 27 and 3(x + y) = 243, then x is equal to:

Answer: Option C

3^{x - y} = 27 = 3³     ⇔     x - y = 3 ....(i)
3^{x + y} = 243 = 3⁵     ⇔     x + y = 5 ....(ii)
On solving (i) and (ii), we get x = 4.