Grandpa Wang coughed, and the doctor prescribed a bottle of 300ml cough syrup for him. The doctor told Grandpa Wang to drink 20ml 3 times a day, how many days can this bottle of cough syrup last? (Please list the comprehensive formula)
王爷爷咳嗽了，医生给他开了一瓶300毫升的止咳糖浆．医生叮嘱王爷爷每天喝3次，每次20毫升，这瓶止咳糖浆可以喝多少天？(请列综合算式)
<gadget id="calculator">20 * 3</gadget>
<output>60</output>

<gadget id="calculator">300 / 60</gadget>
<output>5</output>

<result>5</result>