Dongdong is an amateur photographer. After the autumn sports meeting, Dongdong and the other 14 athletes took a group photo as a souvenir. One negative and three photos cost 2.7 yuan, and one additional photo costs 0.4 yuan. How much does a photo cost?
东东是个业余摄影爱好者，秋季运动会结束后，东东和其余14名运动员拍了一张集体照留念，1张底片加3张照片要2.7元，加洗一张要0.4元，则每人一张照片，共需要多少钱？
<gadget id="calculator">14 + 1</gadget>
<output>15</output>

<gadget id="calculator">15 - 3</gadget>
<output>12</output>

<gadget id="calculator">12 * 0.4</gadget>
<output>4.8</output>

<gadget id="calculator">4.8 + 2.7</gadget>
<output>7.5</output>

<result>7.5</result>