Tolong dijawab beserta caranya

(a-x)/x = y/(b-y)
xy = ab-bx-ay+xy
bx = ab - ay
bx = a(b-y)
b-y = bx/a
y= b - (bx/a)

luas = xy = x(b - (bx/a) = bx - (b/a)x^2
agar maksimum, maka turunan pertama fungsi luas = 0
b - 2b/a x = 0
2bx/a = b
2bx = ab
2x = a
x = a/2
y = b - b(a/2)/a = b - b/2 = b/2

xy = (ab)/4.....(A)