Have to throw in my 2 cents here. I had a Schwinn and was it ever heavy! Heaviest bike I have ever owned to date. The red one is $30??? Definitely worth that. And it is a mixte. We have had this discussion before. It's the seat stays, not the top tube that determines whether or not it's a mixte.

From Sheldon Brown himself:

Mixte
A style of lady's frame in which the "top tube" consists of a pair of small diameter tubes running more-or-less straight from the upper head lug, past the seat tube, and on to the rear fork ends. A mixte frame thus has 3 sets of rear stays, instead of the usual two. A variant on the mixte uses a single, full sized top tube running from the upper head tube to the seat tube, but retains the middle set of stays. A lady's type bike that lacks the middle pair of stays is not a mixte.