Always think of para qué as for what purpose. It is used a lot in Spanish, in cases where it would be improper to use por qué, which really means for what reason.
In English, we use why for both---so it's wise to take a step back and differentiate the two, before translating.
but, technically "why:" should be "porque", no? Para que literally mean "for what" and should be accepted as well as "why". These new sentences need some serious editing. Duo has no trouble with awkward (usuually literal) English when it suits it, but then it changes its mind and wants less literal translations at other times.
I had this as a listen and write thing, and I wrote ¿Para qué quiere cincuenta pesos?, as in the formal form without the usted. It marked me wrong. I get that there's a significant difference between quiere and quieres, but I don't get why it should matter in this instance, as both seem correct to me. It accepts the formal version without the usted all the time, so why not here?
You don't need to. I'm a contributor for another course. When I look at the reports I see the answer or use your submitted. If the answer is valid I click the green button and add it to the database. Most of the time, use your submit answers with typos or other mistakes, and I hit the red button which deletes it.