Answer:
After-tax cost of borrowing = Interest rate x (1-tax rate)
Part a)
Since Bella can’t deduct the interest payments on the loan taken from the dealer in her tax return, after-tax cost of borrowing will be the same as stated interest rate. So, the after-tax cost of borrowing from the dealership will be 5%.
Part b)
After-tax cost of borrowing for second mortgage = 7% x (1-25%)
After-tax cost of borrowing for second mortgage = 5.25%
Part c)
It is evident from the above two answers that borrowing loan from the dealer is less costly for Bella.
Part d)
Yes, Bella must consider the level of her first mortgage loan. If Bella opts for the second mortgage loan and if she is unable to pay her mortgage, she may lose her home due to this loan. So, she must check first, if she is able to pay the loan on time.