support complex expression in left hand side of constraint

currently drools does not support the following syntax:
...
Number($var8 : longValue , ((longValue) * (1.5)) < $var7) from ...
...
(results in "no viable alternative at input ')' in...")

however, this works fine if the condition is re-written like this: "longValue < (($var7)/1.5)"

it would be nice if drools knew how to cope with the condition in its original form as well.