Question 25579
Since we don't know what the numbers are, let's say "X" is one of the numbers and "Y" is the other. 

1.  X + Y = 400 - 216  or 

2.  X + Y = 184

1.  6X - 400 = 2Y + 24...At this point you're going to try to isolate(leave alone) the X and the Y together. So you must add the -400,on the left side, by  +400,
 or -400 + 400 = 0 (400 - 400 = 0)

2.  Now, since you added the 400 on the left side, you must do the same on the right side. 24 + 400 = 424

3.  So far we have, 6X = 2Y + 424. Now, to isolate the X and Y, Subtract 2Y from the "2Y" on the left. 2Y - 2Y = 0.

4. Since you subtracted 2Y from the left side, you must now add it to the right side. 6X + 2Y = 424

5.  Now what number can be divided by 6X + 2Y ?...2(3X = Y)...Divide 6X by 2 = 3X, and 2Y by 2 = Y, that's how you get 2(3X + Y).

6.  Since your multiplying the "2" by "(3X + Y)", you also divide it. 

7.  Since you divided it from the left side, you must divide it from the right. 424 divided by 2 = 212

8.  So far we have 3X + Y = 212.  Now let's return to  #2 on the very top: X + Y = 184... Now you figure out what two numbers fill those slots (X and Y).

9. Now "you" find out X and Y . Remember: 3X + Y = 212 and X + Y = 184 (hint: one of the numbers turned around is 48)   
    ^_^