There aren't that many four digit numbers divisible by 625. Calculator bash time. Due to parity, only check 625 x odd numbers.
After that, there aren't many left. Time to use some more logic, I presume, but I'm lazy and won't do it.
Tricky problems always require some logic. I think we can rule out 1, 2, 3, 4, 5, 7, and 8 due to the parameters put forth in the problem.
Hmm... Perhaps it won't help us that much... I mean, what can we do next?
Nevermind. We can use modulo, though why you're doing AIME Problem #8 is beyond me.
Notice that the digits before \(abcd\) are not at all that important. Beyond that, I'm still thinking. Perhaps try modulo arithmetic? d has to be 1, 5, or 6.
Average speed = total distance traveled/total time it took.
The trip took 5 hours in total and they travelled 160 miles, giving you an average speed of 160/5 = 32 mph.
Please don't post another question unless it is completely different from the problems you're familar with and/or you're truly stuck.
See, just apply your prior knowledge to your current situation! I cannot stress that enough!
Then just repeat what he did if you understand it.
This is almost identical to the problem that guy JUST showed you, only simpler. Do you see why?
