Verified answer

а) (t-3)*(t+5) = t^2+5t-3t-15 = t^2+2t-15

b) (4x-7)*(3x-8) = 12x^2-32x-21x+56 = 12x^2-53x+56

c)(b-2)*(b^2+3b-4) =b^3+3b^2-4b-2b^2-6b+8 = b^3+b^2-4b+8