Explanation:
first of all, J32 does NOT stay empty. it receives the string "0", if none of the 3 conditions is true. otherwise it gets the result of I32/H32.
but with what logic do you want to introduce this new condition ?
should that check happen before the checks of I32, H32 ? or after ?
in other words, should J32 be "0", if one of the checks on I32 and H32 are true, and only if all 3 checks fail, we check H30 ? or is it the other way around ?
I assume the first case.
so, your updated statement looks like
=IF(OR(I32=""; H32="BAJA"; H32="VACAS");"0"; IF(H30="FESTIVO";J32*1.75;(I32/H32))
so, we have I32/H32 only as the truly last-last result option. only if everything else fails.