12 adults take 4 children to visit the World Dinosaur Valley. The ticket price for adults is 60 yuan each, and the ticket price for children is 30 yuan each. How much do they need to buy tickets? (column comprehensive formula calculation)
12个成年人带着4个孩子到世界恐龙谷游览，成人票价为每张60元，儿童票价为每张30元，他们购票需要多少钱？(列综合算式计算)
<gadget id="calculator">60 * 12</gadget>
<output>720</output>

<gadget id="calculator">30 * 4</gadget>
<output>120</output>

<gadget id="calculator">720 + 120</gadget>
<output>840</output>

<result>840</result>