Class 2 and 3 are going to buy books and donate them to the children in the disaster area. "Encyclopedia for Juveniles" is 12 yuan each. I bought 10 copies first, and then bought 5 more copies. How much was the total cost?
二3班准备买书捐给灾区小朋友．《少年百科全书》每本12元，先买来10本，后来又买了5本，一共用去多少元？
<gadget id="calculator">12 * 10</gadget>
<output>120</output>

<gadget id="calculator">12 * 5</gadget>
<output>60</output>

<gadget id="calculator">120 + 60</gadget>
<output>180</output>

<result>180</result>