The rough calculation using APR is done using 13,500 1) but we know that the APR includes Acceptance and Settlement costs and interest - so why don't we use 16,435 to work out the APR?
Your friend has borrowed £13,500. To work out the APR, you set this, the present value of the loan, equal to the present value of the payments, ie 13,500 = 140+[(12x337.50)x annuity over 4 years paid monthly + 95v^4].
