$18-3.$ Greg Lance has just been informed by a finance company that he can access a line of credit of no more than $$75,000$ based upon the equity value in his home. Lance still owes $$180,000$ on a first mortgage against his home and $$25,000$ on a second mortgage against the home, which was incurred last year to repair the roof and driveway. If the appraised value of Lance's residence is $$400,000,$ what percentage of the home's estimated market value is the lender using to determine Lance's maximum available line of credit?