Let the two numbers be x and y. then according to question x+y=9 ........ (i). also
1
x
+
1
y
=
1
2
⇒x+y=
xy
2
........... (ii) from (1) and (2) xy=18 ....... (iii) from (1) x=9−y putting x in eqn (3) (9−y)y=18 ⇒y2−9y+18=0 (y−6)(y−3)=0 ⇒y=6,3 ∴ One of the no.'s 6 or 3