I believe it b I am sorry if iam wrong
"Product" means we are looking at a multiplication problem.
Can be written as:
A number (n) times 50
n x 50
The simplest (and most common way) to write it:
50n
First you would distribute through the parenthesis
-10x+2+7(5x-1)-3(-5x+1)
Then distribute
-10x+2+35x-7-3(-5x+1)
And then distribute 3
-10x+2+35x-7+15x-3
Collect like terms
40x+2-7-3
40x-8 is your answer :)