Question 96991
Let x and y be the 2 numbers 

then we have 

x + y =33  ........(1)  (Sum is 33 )
and
x - y =9   ........(2)  (difference is 9 )

adding 1 and 2 

2x = 42 
x= 21

Substituting the value of x in 1
21 + y = 33
y = 33-21
y= 12

Numbers are 21 and 12