Using the speed - distance relationship, Marcie's time will be 6 hours. Hence, she'll match her parents time.
Recall :
To obtain Marcie's time :
We can solve for y thus :
y × 18 = 108
y = 108 / 18
y = 6 hours
Since, Marcie's will cover the same distance in 6 hours, the she'll match and surpass her parents time.
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