I did them in this order: A, B, D. I skipped C precisely because the conversion would've been too time-consuming. The first thing you should try to do in a multiple choice problem is get rid of options. Working against the clock, I just do the fastest ones first, and see what drops out.
As far as the math goes I can't really give you a trick. I did it the first way--but depending on how comfortable you are with mental math, the second method might be easier.
A) something times twenty-five is a nice multiple of ten. Two times twenty-five is fifty which is neatly divisible by ten.
B) as above. X*10 is neatly divisible by 30--X is 3.
C) skipped
D) 4/5 is close to a whole, 5/13 isn't even a half. False.
The above might be easier, or this:
If you take the inverse of these, you end up with easier denominators: remember to switch the test statement. After modifying them:
A) (25/2) < (10/1). 25/2 is a little more than 12, which is bigger than 10. false.
B) 10 is equal to 10. false.
C) 28/2 > 35/3. 28/2 is 14, but 35/3 is about 12. true.
D) 13/5 = 5/4. 13/5 is almost 3, but 5/4 is just more than 1. false.