During the "June 1st" period, Xinhua Bookstore held a "buy four, get one free" campaign. Teacher Wang bought 15 of the same storybooks and paid a total of 120 yuan. How much is the original price of each storybook?
"六一"期间，新华书店举行了"买四赠一"活动，王老师买15本同样的故事书共付120元，每本故事书原价多少元．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">15 / 5</gadget>
<output>3</output>

<gadget id="calculator">15 - 3</gadget>
<output>12</output>

<gadget id="calculator">120 / 12</gadget>
<output>10</output>

<result>10</result>