Hi guys.
Long time lurker, first time poster. 
I trade on OptionsXpress.
General question:
Can I finance a debit call spread with a credit put spread in the same trade?
For example, FFIV for Jan 18 expiry:
Debit call spread 160/170: Debit 5.60
Credit put spread 130/120: Credit 2.30
Net debit for the whole trade: 3.30