Question 145258
find the slope m = {{{(73.7-70.6)/(6-0)}}} = {{{0.5166}}}

Use point slope to find the equation
(E - 70.6) = 0.5166(t - 0)   <---you used coordinates from two different points

E(t) = 0.5166t + 70.6

Find E in year 2003
t = 2003 - 1991 = 12

E(12) = 0.5166(12) + 70.6  = 76.8