diff --git a/polynom.hs b/polynom.hs
index ae52e02..bb88b0b 100644
--- a/polynom.hs
+++ b/polynom.hs
@@ -1,5 +1,6 @@
 data Atree = Number Int | Variable String | Plus Atree Atree | Minus Atree | Times Atree Atree
 
+-- (5 - x) * (2y - (x + 7)))
 t :: Atree
 t =
   Times
@@ -14,4 +15,8 @@ type Polynomial = [Monomial]
 type Monomial = (Int, [String])
 
 polynomial :: Atree -> Polynomial
-polynomial = undefined
+polynomial (Number n) = [(n, [])]
+polynomial (Variable v) = [(1, [v])]
+polynomial (Plus e1 e2) = polynomial e1 ++ polynomial e2
+polynomial (Minus e) = map (\(c, xs) -> (-c, xs)) (polynomial e)
+polynomial (Times e1 e2) = concatMap (\(c1, xs1) -> map (\(c2, xs2) -> (c1 * c2, xs1 ++ xs2)) (polynomial e2)) (polynomial e1)