You can bunk.
But you can't be stupid about it.

Add Subject

Formulas used:

Attendance = (Attended ÷ Total) × 100

Classes needed: solve (A+x)/(T+x) ≥ target

Bunk allowance: solve A/(T+x) ≥ target

Quick formulas

Attendance: (A ÷ T) × 100 · Classes needed: (A+x)/(T+x) ≥ target · Bunk: A/(T+x) ≥ target