the answer is 80
you divide 64 by the numerator, 4, which gives you 16, which you then multiply by the denominator, in this case it is 5, 16 x 5 equals 80.
"They did not fear the Trojans' powerful attack, they stood their ground LIKE clouds set in place by Zeus." The point of the simile is to show that the Danaans stood up for themselves.