Explanation:

The Sum of the square of two numbers is 80"
x^2 + y^2 = 80
" and the square of their difference is 36."
(x - y)^2 = 36
Foil (x-y)(x-y)

x^2 - 2xy + y^2 = 36
Use elimination, subtract from the 1st equation
x^2 + 0xy + y^2 = 80
x^2 - 2xy + y^2 = 36
Subtraction eliminates, both x^2 and y^2
2xy = 44
Divide both sides by 2
xy = 22

Hence, option 2 is the correct answer.