Ok so you need the surface area formula of a cone.
A = πrl + πr∧2
where π = 3.14 (pi)
r = half of the diameter (18/2 = 9)
l = slant hight ( 22 )
Slot this into the equation A = (3.14 [ rounded] )(9)(22) + (3.14 [ rounded] )(9)∧2 = 876.06 this is due to the rounded pi the answer is 876.5 i.e the third.
Hope this helps :D.
