Question 170919
look at the x first

 20x^1 1y^2 + 4x^1 1y^1 - 15x^1 1y^2 - 3x^1 1y^1 - 5x^1 1y^2

20x^1 + 4x^1 -15x^1 - 3x^1 - 5x^1   =  x^5

now look at the y

 y^2 + y^1 + y^2 + y^1 + y^2 = 5y^8

        so your answer is   x^5(5y^8)