The number of ducks, D, (in thousands) and geese, G, (in thousands) that migrate from 1980 to 2000 can be modeled by the equations:

D = -120 + 294.1t - 184.4t + 50.2t3, 1 < t < 21

G = -188 + 579.6t - 403.3t + 97.8t3, 1 < t < 21

Where t represents the year, with t = 1 corresponding to 1980.

a) Find a radical expression that models the total number, T, of birds that migrated from 1980 to 2000.

T = -68 + 873.7t - 218.9t + 148tt

T = -308 + 1021tt - 587.7t

T = -68 + 285.5t - 218.9t + 47.6tt

T = -308 + 873.7t - 587.7t + 148tt