Mom bought 4 rolls of film for a total of 84 yuan, and each roll can take 36 photos. How much is each roll of film?
妈妈买来4卷胶卷，共花84元，每卷可拍36张照片．每卷胶卷多少元？
<gadget id="calculator">84 / 4</gadget>
<output>21</output>

<result>21</result>