Question 1075365
(a)


Plug t = 0 into the z equation to get


z = 120 - 5*t
z = 120 - 5*0
z = 120 - 0
z = 120


This means that when the time is t = 0 minutes, they are at z = 120. 


The tower is 120 feet tall.


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(b)


The child will reach the bottom when z = 0


Plug z = 0 into the z equation and solve for t


z = 120 - 5*t
0 = 120 - 5*t
0 + 5*t = 120 - 5*t + 5*t
5*t = 120
5*t/5 = 120/5
t = 24


The child will reach the bottom at t = 24 minutes


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(c)


Unfortunately I don't have enough information to answer this problem. You wrote "tt" but didn't write any values after that. Please update the problem. Thank you. 


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(d)


As in part (c), the same issue happens with this part as well. There isn't enough information. Please update.