Just treat the whole number part as a whole number. In this case, just leave it first as -6. Let's proceed to converting 0.59 to fraction..
59/100 = 59/100 (no more simplest form)
So, using mixed fractions, the converted version is \(-6 \frac{59}{100}\)
Using improper fractions, it is \(\frac{-659}{100}\)