Simplify the product using foil. (2x – 7)(5x 5)

FOIL is an 'acronym'.  It helps you remember how to multiply
two binomials ... like  (2x-7)  and  (5x+5) .

FOIL stands for "First, Outside, Inside, Last".  Here's how it's used
to multiply these particular two binomials:

                 (2x - 7) (5x + 5) 

First:        (2x) (5x) = 10x²

Outside:  (2x) (5) = 10x

Inside:     (-7) (5x) = -35x

Last:        (-7) (5) = -35

Add them all together, and you have the product:

                             10x² + 10x -35x -35

Simplify the sum:  10x² - 25x -35

     or                    5(x² - 5x - 7) .

There is no association.