Evan’s family drove to a theme park for vacation. they drove the same speed throughout the trip. the first day, they drove 300 miles in 6 hours. the second day, they drove 250 miles in 5 hours. the third day, they arrived at the park after driving for 3 hours. how many miles did they drive on the third day?

Evan's family drove 150 miles on the third day.

Explanation:
Because they had driven the same speed throughout the trip, dividing the miles driven by the hours would result in the miles that they drove per hour. 300/6 and 250/5 = 50. So, Evan's family drove 50 miles per hour. To solve for the hours driven on the third day, you need to multiply the hours driven by the miles that were driven per hour. 

3 hrs. x mph (miles per hour) = miles driven on the third day

Hope this helps! Sorry, I don't have the time to reread my answer, but I'm positive that it'll make sense to you somewhat.

If they drove the same speed for the entire trip, all you need to do is calculate the speed and multiply it by the number of hours drove.

If they drove 300 miles in 6 hours, then they are driving at 50 miles per hour.

That means on the third day, since they drove for 3 hours, they driven a total of 50 x 3 miles or 150 miles.