One number is 8.7, which is 4.2 more than the other number. What is the sum of the two numbers? What is the correct column
一个数是8.7，它比另一个数多4.2，两个数的和是多少？正确的列式是多少
<gadget id="calculator">8.7 - 4.2</gadget>
<output>4.5</output>

<gadget id="calculator">4.5 + 8.7</gadget>
<output>13.2</output>

<result>13.2</result>