11) Factors of 55 are 1,5,11,55 Factors of 75 are 1,3,5,15,25,75
The greatest common factor is 5.
12) With algebraic expressions you just simplify and multiplier in the simplification is the greatest common factor.
66yx + 30x^2y --) 6yx( 11 + 5x ) so the greatest common factor is 6yx.
13) 60y + 56x^2 --) 4( 15y + 14x^2 ) so the greatest common factor is 4.
14) 36xy^3 + 24y^2 --) 12y^2( 3xy + 2 ) so the greatest common factor is 12y^2.
15) 18y^2 + 54y^2 --) 18y^2( 1 + 3 ) so the greatest common factor is 18y^2.
16) 80x^3 + 30yx^2 --) 10x^2( 8x + 3y ) so the greatest common factor is 10x^2.
17) 105x + 30yx + 75x --) 15x( 7 + 2y + 5 ) so the greatest common factor is 15x.
18) 140n + 140m^2 + 80m --) 20( 7n + 7m^2 + 4m ) so the greatest common factor is 20.
If you want a further explanation step by step just ask :)
