Find and prove the inequality that 1 / x + 1 / y is greater than or equal to 4 / x + y

Find and prove the inequality that 1 / x + 1 / y is greater than or equal to 4 / x + y

Cauchy inequality
(1/x+1/y)(x+y)>=(1+1)^2=4
So 1 / x + 1 / Y > = 4 / (x + y)