y=2x+5 and y-x=8. Find x and y.

The expression (2x+5) has the same value as y, and so we can use (2x+5) instead of y in the second equation. This means that we are now just dealing with one variable (x) instead of two (x and y). If we make the substitution for y, the second equation becomes: (2x+5)-x=8. We can simplify this by collecting the x terms together. 2x-x is just one x, so we are left with x+5=8. We can now solve this to find x by subtracting 5 from both sides: x=8-5, which is 3, so x=3. We can put this value for x back into one of the original equations to find y. We know that x is 3, and so the first equation, y=2x+5, becomes y=(23)+5. 23 is 6, and 6+5 is 11, so y=11. Finally, we can check these values for x and y by substituting them into the second equation (y-x=8). This would be 11-3=8, and as this works out, we know our values for x and y are correct.