Question 724528
Let the two numbers be a and b

As per the question , 
a+b = 33 ------(i) marked this equation as (i)

a-b = 9 ------(ii)

(i) + (ii) , we get

2a = 42

=> a = 42/2 = 21

similarly from (i) - (ii) , we get
b = 12