The table below shows (lifetime) peptic ulcer rates (per 100 population), U, for various family incomes, x, as reported by the 1989 National Health Interview Survey.
Income 4000 6000 8000 12000 16000 20000 30000 45000 60000
Ulcer rate 12.9 12.8 12.4 11.9 12.3 11.1 10.5 8.5 7.2
(a) Find the equation of the regression line.
