Teacher Wang bought two reference books. "Primary Mathematics Teaching Guidance" is 12.36 yuan, and "Mathematics Handbook" is 4.25 yuan more than "Primary Mathematics Teaching Guidance". Teacher Wang gave the salesperson 50 yuan, how much should I get back?
王老师买了两本参考书．《小学数学教学指导》12.36元，《数学手册》比《小学数学教学指导》多4.25元．王老师给了售货员50元，应找回多少钱？
<gadget id="calculator">12.36 + 4.25</gadget>
<output>16.61</output>

<gadget id="calculator">50 - 12.36 - 16.61</gadget>
<output>21.03</output>

<result>21.03</result>