Correct Option: C

The average of the three numbers x, y and z = 45.
⇒ x + y + z = 3 × 45 = 135 ...(i)

x =	y + z	+ 9
	2

⇒ 2x – y – z = 18 ...(ii)

and,	y + z	= y + 2
	2

⇒ y + z = 2y + 4
⇒ z – y = 7 ...(iii)
By equations (i) + (ii),
3x = 135 + 18 = 153
⇒ x = 51
By equations (i) and (iii),
x + y + z + z – y = 135 + 4 = 139
⇒ x + 2z = 139
⇒ 51 + 2z = 139
⇒ 2z = 139 – 51 = 88
⇒ z = 44
∴ x – z = 51 – 44 = 7