8−2+58−2+5. if harry's answer is hh and terry's answer is tt, what is h−th−t?

The correct answer is  67 .

If Harry and Terry didn't both get the same answer, then
at least one of them, and maybe both, made a mistake. 

We have no way of knowing what mistakes were made,
or by whom, so we have no way of knowing what answer
either of them got.

The question can't be answered with no more than the
given scant information.

108