1)what volume of air was breathed out during one normal exhalation 2)how many times did exhalation take place during one minute of normal breathing
3)how many times did deep exhalation take place in 30 seconds ​

Explanation:

Exhaled air for 90 minutes would be 40 breaths per minute (at 1 litre per breath) x 90 minutes =3600 litres x 0.16= 576 litres of oxygen, In other words, first work out the amount of air breathed out in litres/minute and then multipy by the number of minutes to get the total litres of air breathed out and then multiply that figure by 0.16 (16 % oxygen per volume of air) to get total litres of oxygen breathed out

the peaceful equids (horses, donkeys and zebras) were enslaved by the human race to do our bidding -- sorry, domesticated -- several thousand years ago, and since that time they've been an invaluable resource for transportation, agriculture, warfare, companionship and sometimes-horrifying entertainment.