Aunt Zhang brought 50 yuan and bought a pair of table tennis bats and a box of table tennis balls. A pair of table tennis bats was 29.8 yuan, and a box of table tennis balls was 10 yuan. How much should the salesperson get back for Aunt Zhang?
张阿姨带了50元钱，买了一副乒乓球拍和一盒乒乓球，一副乒乓球拍29.8元，一盒乒乓球10元，营业员应找回张阿姨多少元？
<gadget id="calculator">29.8 + 10</gadget>
<output>39.8</output>

<gadget id="calculator">50 - 39.8</gadget>
<output>10.2</output>

<result>10.2</result>