"Altogether, it's 3850 yuan."
It's incredibly aggravating how this one doesn't have hover-over hints for the numbers. I've now gotten this marked wrong twice.
(Dec. 4, 2017) So frustrating, hints still aren't up yet four days later, it would take seconds for someone to address this.
My understanding is that 块 is colloquial, 元 is slightly more formal. To use both may be similar to saying $50 = "fifty bucks dollars." Correct me if I misunderstand it!