The 18 members of the school football team took a group photo for a six-inch photo. The photo studio charged 21 yuan and developed three photos for free. If additional washing is required, it costs 1.6 yuan to wash one sheet. If the football team is going to keep a photo of each person, how much is the average cost per person?
学校足球队18人合影留念，照六英寸照片，照相馆收费21元，并免费洗三张照片．如果需要另外加洗，洗一张需要1.6元．如果足球队准备每人保存一张照片，平均每人需要多少元？
<gadget id="calculator">18 - 3</gadget>
<output>15</output>

<gadget id="calculator">1.6 * 15</gadget>
<output>24</output>

<gadget id="calculator">24 + 21</gadget>
<output>45</output>

<gadget id="calculator">45 / 18</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>