First look for numbers that have a factor in common. Look at (2 x 1) and ( 7 x 2), the common factor is two so we factor.
(2 x 1) + (7 x 2) + (1 +7) ( I moved it around so you can see the factor)
2 (1 + 7 ) + (1+7) ( I factored out the two)
(1+7)(2+1) ( I factored out the (1+7) from problem above)
