So confused in algebra 2

if x^2 + y ^2 = 30 and (x + y)^2 = 56. Find (x - y)^2.
The answer is 4 but I dont know how they got it

(x-y)^2 = (x+y)^2 - 4xy
= 56 -4xy....................(i)
Also
(x+y)^2 = x^2+y^2 +2xy
56 =30 +2xy
2xy = 26 ..............................(ii)
From (i) and (ii)
(x-y)^2 = 56 -2*26 = 56 -52 = 4 ...............Ans