Four people recorded the number of minutes they exercised today. Mackenzie exercised for 3 as many minutes as Brinley. Brinley exercised for 17 fewer minutes than Ariana. Ariana exercised for 3 times as many minutes as Seth Together, Ariana and Mackenzie exercised for 20 more minutes than Brinley and Seth. Let z represent the number of minutes Seth exercised.​