Wang Peng bought two books, one was 7.94 yuan, which was 0.37 yuan more expensive than the other. How much did the two books cost in total?
王朋买了两本书，一本7.94元，比另一本贵0.37元，两本书一共要付多少元？
<gadget id="calculator">7.94 - 0.37</gadget>
<output>7.57</output>

<gadget id="calculator">7.57 + 7.94</gadget>
<output>15.51</output>

<result>15.51</result>