If you divide 64/16, that equals 4, then you multiply 4*3 and your answer is 12. It looks something like this (for "showing your work" purposes);
64/16=4
4 x 3=12
answer=16 cups of sugar for 64 bags of tea
Use cos^-1(0.6157) and u might find the answer
-----98 with any quantity of any digits before the 9 .
First you find 4/5 of 8 and then 4/5of 7 and multiply them