Add these 2 polynomials

Question

(21t+8)(4t) and (3t-4)(2t)
84t^2+32t 6t^28t
I got this far isnt there another setp to do this is the part I am having difficulty with.

Answer 1

(21t+8)(4t) + (3t-4)(2t) =
84t^2+32t + 6t^2-8t
Combine like-terms:
90t^2 + 24t
Factor out 6:
6(15t^2+4t).