x-y=8 x+y=11

x - y = 8                  (1)

x + y = 11               (2)

 

Add (1) and (2)

2x = 19

x = 19/2 = 9.5

 

Put this back into (2)

9.5 + y = 11

y = 11 - 9.5

y = 1.5

.

x can be 10 and y can be 2: 10 - 2 = 8 

x can be 6 and y can be 5: 6 + 5 = 11 

 

We could mix it up also and do the question x - y = 8 + x + y = 11. 

Which it would go like this: 

x can be 10 and y can be 2: 10 - 2 = 8

Now 8 is three away from 11. 

x can be 2 and y can be 1: 2 + 1 = 3 

8 + 2 + 1 = 11 

Now lets finish our problem by simplifying it all: 

8 + 3 = 11 

 

I Hope That Helped :)