Question 552910
Let the no. be x and y.
 
x + y = 21  ------eq(1)
x - y = 5     ------eq(2)
 
Add eq(1) and eq(2)
now we will eliminate y 'cause +y -y =0
 
2x = 26
  x = 26/2

  x = 13  now we have value of x , put the value of x in  eq(2).

13 - y = 5
 -y = 5 -13
 -y = -8  i;e y = 8

So, the no.s are 13 and 8