A/BC + D/EF + G/HI = 1
Each of three fractions has a one-digit numerator and a two-digit denominator. The three fractions together add up to one. Place the nine digits 1-9 into the fractions to make the equation correct.
(In reply to
Solution by Jim Lyon)
Doh. I've been deliberately forcing the 5 into a denominator as I figured that a 'nice' fraction with a 5 as numerator would end up as 5/X5 or 5/X0, both of which aren't allowed by the question. I was going to look into 'not nice' fractions with 5 as the numerator later... ;-)