Answer:
They will be 170 miles apart at 10 AM
Step-by-step explanation:
Nancy has 15´ of head start which is 1/4 hr.
NHD = 20*(1/4) = 5 miles is her head start
Mark leaves at 7.15hs = starting point
Marks stop at when they are 170 miles apart = t
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t = the time they are 170 miles apart
d= distance in miles Nancy travels in time t
170 - (d+5) = distance in miles Mark travels in time t
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Nancy's equation:
(1) d = 20t
Mark's equation:
(2) 170 - (d+5) = 40t
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(2) 170-d-5=40t
(2) d+40t=165
Substitute (1) into (2)
(2) 20t+40t=165
(2) 60t=165
(2) t=2.75
7:15 AM + 2.75 hrs (2:45hs) = 10 AM
They are 170 miles apart at 10 AM
check:
(1) d=20t
(1) d=20*2.75
(1) d=
55
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(2) 170 - (d+5) = 40t
(2) 170 - (d+5) = 40*2.75
(2) 170 - d-5 = 110
(2) d=55
