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Math·Algebra·Linear equations in two variables

hard

A boat traveled a certain distance upriver and then traveled downriver $10$ miles farther than it traveled upriver. The boat took $x$ hours to travel upriver at a speed of $12$ miles per hour. The boat then took $y$ hours to travel downriver at a speed of $18$ miles per hour faster than the speed at which the boat traveled upriver. Which of the following equations best represents this situation?

A

$12x-30y=-10$

B

$12x+30y=-10$

C

$12x+30y=10$

D

$12x-30y=10$