Peter is trying to work out by completing sit-ups and push-ups in order to gain muscle mass. originally, peter was en sit-ups for every one push-up. completing five sit-ups for every three push-ups, but then he injured his shoulder. after the injury, peter completed the same number of repetitions as he did before his injury, but he completed sev during a training session after his injury, peter completed eight push-ups. how many push-ups was peter completing before his injury?