the difference of 5 and the cube of the sum of x and y

the difference of 5 and the cube of the sum of x and y

The sum of x and y:
x + y

The cube of the sum of x and y means we raise x + y to the 3rd power:
(x + y)^3

The difference of 5 and the cube of the sum of x and y
5 - (x + y)^3