Suppose we try to write out this problem symbolically:
a c 1
-- - --- = --- , b not equal to 5, d not equal to 5
b d 5
Unfortunately, this equation contains 4 unknowns (too many)
We could do a bit of guesswork here:
a c 1
-- - --- = --- , b not equal to 5, d not equal to 5
b d 5
8 6 2
--- - ----- = -----
10 10 10
This is true, but not all that wonderful, because all 3 fractions could be reduced and would then have denominator 5.