<PRE><B>Question 237582</B>
distance = rate * time


t = 1
d = 80 km


first part of the trip, rate * time was .5 * 60
second part of the trip, rate * time will be .5 * x


add the parts together to get the total trip.


.5 * 60 + .5 * x = 80


30 + .5x = 80


subtract 30 from both sides to get:


.5x = 50


divide both sides by .5 to get:


x = 100


confirm by plugging into the original equation to get:


.5 * 60 + .5 * 100 = 80


simlify to get:


30 + 50 = 80 confirming the answer for x is good.


looks like she will have to drive 100 km/h in order to achieve her goal of driving 80 km in exactly 1 hour.


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