Maths problem: how to do part (b) i and ii, thanks.?

(i)
65(x−y)²=17(x+y)²
65(41−2M)=17(41+2M)
65×41−17×41=17×2M+65×2M
48×41=82×2M
48×41=4M×41
M=12

(ii)
x⁴+y⁴
=(x²+y²)²−2x²y²
=41²−2M²
=1393