Calculate IRR for the following buy-out opportunity.

Company has $125m EBITDA at entry, multiple of 10, debt 50% of consideration paid. Company exited year 5, $175m EBITDA, multiple of 12, 50% of original debt remaining.

1. Whats the IRR?
2. Whats the IRR if you only change exit multiple to 14?
3. Whats the IRR if you only change exit year to 6 vs 5?
4. Whats the IRR if you only change entry debt to 60% from 50%, still 50% of original debt left at exit?