With most of the IVA companies they would work it out as 85% of £75000 is £63700 which is less than the £64300 so no equity.
There is one or two trying to take a stance on it being you have equity of £74995 less £64300 = £11595 and so you would have to try and put in £9955 which is wrong in most peoples views with them also not "sharing" the equity between the two of you.