Updated!
Upgrading from 80-90 only costs 10 TPE / point, so you actually only spent 10 instead of 15. The unspent has been added to your bank, bringing your banked TPE to 13.
Upgrading from 80-90 only costs 10 TPE / point, so you actually only spent 10 instead of 15. The unspent has been added to your bank, bringing your banked TPE to 13.