Maud, a calendar year taxpayer, is the owner of a sole proprietorship that uses the cash method. On February 1, 2018, she leases an office building to use in her business for $120,000 for an 18-month period. To obtain this favorable lease rate, she pays the $120,000 at the inception of the lease. How much rent expense may Maud deduct on her 2018 tax return?