If a/b = 4/5 and b/c = 15/16, then (c²-a²) / (c²+a²) is:

a/c = (a/b) * (b/c) = (4/5) * (15/16) = 3/4। मान लीजिए a=3, c=4। (16-9) / (16+9) = 7 / 25।