Question 54167
You need to multiply 2x times everything in the second parenthesis and then multiply -1 time everything in the second parenthesis and then combine like terms.  Like terms are terms that have the very same variables to the very same power:
(2x-1)(10x+1)
{{{2x(10x)+2x(1)-1(10x)-1(1)}}}
{{{20x^2+2x-10x-1}}}
{{{20x^2+(2-10)x-1}}}
{{{highlight(20x^2-8x-1)}}}
Happy Calculating!!!