Respuesta :

(1)1.3t^3 +t^2 -42t +8
(2)1.3t^3 + t^2 -6t +8
(3)1.9 t^3.+ 8.4^t^2 -42t
(4)1.9t^2 -42t + 8

I hope I got that right!!
okay, now they are all separated in columns, add the ones with the same powers (e.g (1)_ 1.3t^3 + (2) 1.3t^3 + (3) 1.9 t^3 = 4.5t^3.  

1.3t3 + t2 – 42t + 8