256.
The coefficient of just the y term would be 256 because the entire expanded equation looks like this:
y^4+16y^3+96y^2+256y+256
Whenever a number is followed by percent, you can turn it into a fraction by simply moving the decimal places two places to the left:
90.0 % becomes .90
As a fraction, this is 90 over 100. To reduce it to its simplest form, divide by 10:
9/10
