>> t=[1, 1.5, 2, 2.5, 3 , 3.5 , 4];
>> f=[33.4, 79.5, 122.65, ...159.05, 189.15, 214.15, 238.65];
>> plot(t, f, '.');
>> polyfit(t, f, 1)

ans =

   67.9679  -21.8411