Green grass can renew the air. 1m**2 of green grass can release about 15g of oxygen and absorb about 20g of carbon dioxide every day, and each person inhales 750g of oxygen and emits 900g of carbon dioxide every day. How many square meters of green grass is needed per person per day ?
绿草能更新空气，1m**2的绿草每天可以放出约15g的氧气，吸收约20g的二氧化碳，而每人每天吸入氧气750g，排出二氧化碳900g，每人每天至少需要多少平方米的绿草地？
<gadget id="calculator">750 / 15</gadget>
<output>50</output>

<result>50</result>