4 times of the sum of the cubes of x and y

4 times of the sum of the cubes of x and y

The cube of x means we raise x to the 3rd power:
x^3

The cube of y means we raise y to the 3rd power:
y^3

The sum of the cubes means we add:
x^3 + y^3

4 times the sum of the cubes:
4(x^3 + y^3)