I can show you how to get started:
CODE
call Recur(5)
call Recur(4) -x
call Recur(3) -x
call Recur(2) -x
call Recur(1) -x
return
x=3+1=4
call Recur(1) -y
return
y=4+5=9
call Recur(2) -y
call Recur(1) -x
return
x=4+1=5
call Recur(1) -y
return
y=5+9=14
y=5+14=19
call Recur(3) - y
call Recur(2) - x
...etc...
The best thing to do is to write the program and put a few print statements in it to see whats going on.