Denise used 360 minutes out of 450 minutes. You would set this up as a fraction. Then, you would have to find out the percentage of how much Denise used. You would put 360/450 across from x/100. You find the value of x by multiplying 360*100 which equals 36000. You then would divide it by 450 to get a product of 80. This is how you would get 80%.
