Apples are 12 yuan per kilogram, and bananas are 7 yuan per kilogram. Mom buys 15 kilograms of these two kinds of fruits. How much is the total cost?
苹果每千克12元，香蕉每千克7元，妈妈买这两种水果各15千克，共花多少元？
<gadget id="calculator">12 * 15</gadget>
<output>180</output>

<gadget id="calculator">7 * 15</gadget>
<output>105</output>

<gadget id="calculator">180 + 105</gadget>
<output>285</output>

<result>285</result>