Isaiah and Allison Burton have a home with an appraised value of $180,000 and a mortgage balance of only $90,000. Given that an S&L is willing to lend money at a loan to-value ratio of 75 percent, how big of a home equity credit line can Isaiah and Allison obtain? How much, if any, of this line would qualify as tax deductible interest if their house originally cost $100,000?