In what proportion should 5% and 1% hydrocortisone ointments be mixed to prepare a 2.5% ointment?

In what proportion should 5% and 1% hydrocortisone ointments be mixed to prepare a 2.5% ointment?

In what proportion should 5% and 1% hydrocortisone ointments be mixed to prepare a 2.5% ointment?