The easiest method of multiplying polynomials, in my experience, is the FOIL method. Honestly, I couldn't tell you what the letters stand for anymore, but I definitely remember how to do it. It's just distribution.
(6x+1)(5x+8)
Multiply the 6x by 5x and 8, then the 1 by 5x and 8:
30x²+48x+5x+8
Then combine like terms:
30x²+53x+8