Sixth grade students in a certain school are going to ski. If they rent a 45-seat bus, 15 of them will have no seats. If they rent the same number of 60-seat buses, one bus will be empty. It is known that the rent of a 45-seater bus is 220 yuan, and that of a 60-seater bus is 300 yuan. How many sixth graders are there in this school?
某校六年级学生要去滑雪，若租用45座客车，则15人没有座，若租用同样数目的60座客车，则一辆客车空着．已知45座客车租金220元，60座客车租金300元．这个学校六年级学生有多少人？
<gadget id="calculator">60 + 15</gadget>
<output>75</output>

<gadget id="calculator">60 - 45</gadget>
<output>15</output>

<gadget id="calculator">75 / 15</gadget>
<output>5</output>

<gadget id="calculator">45 * 5</gadget>
<output>225</output>

<gadget id="calculator">225 + 15</gadget>
<output>240</output>

<result>240</result>