There are 420 story books and 15 times more science books than story books. How many story books and science books are there in total?
学校图书馆运来一批新书，故事书有420本，科技书是故事书的15倍，故事书和科技书一共多少本？
<gadget id="calculator">420 * 15</gadget>
<output>6_300</output>

<gadget id="calculator">6_300 + 420</gadget>
<output>6_720</output>

<result>6_720</result>