Carrie is travelling at a constant speed of $85 \mathrm{~km} / \mathrm{h}$. If Carrie is halfway through a $510 \mathrm{~km}$ trip, how much longer will the trip take?
(A) 5 hours
(B) 425 hours
(C) 12 hours
(D) 1.5 hours
(E) 3 hours
Solution 1

Travelling at a constant speed of $85 \mathrm{~km} / \mathrm{h}$, the entire $510 \mathrm{~km}$ trip would take Carrie $510 \div 85=6$ hours.

Since Carrie is halfway through the $510 \mathrm{~km}$ trip, then the remainder of the trip will take her half of the total trip time or $6 \div 2=3$ hours.

## Solution 2

Carrie is halfway through a $510 \mathrm{~km}$ trip, and so she has half of the distance or $510 \div 2=255 \mathrm{~km}$ left to travel.

Since Carrie travels at a constant speed of $85 \mathrm{~km} / \mathrm{h}$, then it will take her $255 \div 85=3$ hours longer to complete the trip.

ANSWER: (E)