B because the amount of money they earn per hour multiplied by how many hours they worked is equal to what they earned in total
The students will earn $180 by washing cars for 9 hours.
In 3 hours the students will earn...
$5 x 12 = $60
5 dollars x 12 cars = 60 dollars
So in 3 hours the group of students will earn $60
In 9 hours the students will earn...
$60 x 3 = $180
Since the students will earn $60 per every 3 hours, you multiply $60 with 3 because if you divide 9 hours by 3 hours you will get 3. The answer you get by multiplying 60 by 3 is 180. Therefore the students can earn $180 from washing cars.
I hope this helps!
They have a scale factor of 5:6 so first we need to find the perimeter of KLM:

Then apply the scale factor of 5:6:

Set the denominators equal:

So we see that the perimeter of GHJ is 35.