The sum of five integers arranged in a row is 60, and each number is 3 greater than the previous number. What is the largest of these five numbers?
五个排成一列的整数之和是60，每一个数比前一个数大3，这五个数中最大的是多少．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">6 + 12</gadget>
<output>18</output>

<result>18</result>