The greatest common factor of two or more numbers is the greatest common factor of the two or more numbers that can divide the numbers without remainder. Factors of 60x^4y^7, 45x^5y^5 and 75x^3y. 60x^4y^7 = 2, 2, 3, 5, x, x, x, x, y, y, y, y, y, y, y 45x^5y^5 = 3, 3, 5, x, x, x, x, x, y, y, y, y, y 75x^3y = 3, 5, 5, x, x, x, y The common factors are 3, 5, x, x, x, y = 15x^3y (the second option).