how about (5-3)x2 + 8(5-2) ?

To me these are really just "puzzles" and do not actually require much mathematical ability.
The best and often only way is to by 'trial and error'.

what is the rule when grouping numbers?
example I want the answer to be 28.
5 - 3 x 2 + 8 x 5 - 2 = 28

I tried
5-(3 x 2) + 8 (5 - 2) but it equaled 23

help