Li Xia bought a pencil with a price tag of 4.25 yuan and a pencil case with a price tag of 11.85 yuan. After she paid the salesperson one RMB, the salesperson got back 33.9 yuan. What is the denomination of RMB that Li Xia paid?
李霞买了一支标价为4.25元的铅笔和一个标价为11.85元的笔袋，她付给营业员一张人民币后，营业员找回了33.9元．李霞付出的一张面额多少的人民币？
<gadget id="calculator">4.25 + 11.85 + 33.9</gadget>
<output>50</output>

<result>50</result>