Problem : Remove the common factors of 25x3 +30x2 - 60x.

5x(5x2 + 6x - 12)

Problem : Remove the common factors of 120x5 -210x3 +150x4.

30x3(4x2 - 7 + 5x)

Problem : Remove the common factors of 16xy4 +4x2y3 -12x5y4.

4xy2(4y2 + xy - 3x4y2

Problem : Remove the common factors of 49x2y2 -70x3y3 +7x5y2.

7x2y2(7 - 10xy + x3)

Problem : Remove the common factors of 27x12y4z - 27x3y4z2 +27x10y4z - 4x4y5z3.

x3y4z(27x9 -27z + 27x7 -4xyz2)

Problem : What monomial does the represent?
16x4 -80x3 + = 8x3(2x - 10 + 3x2)

= 24x5