first, you put 15 over 100 then to the right, P over 31.00. Then, you multiply 15 x 31 and get 465. Now, put 465 over 100 and then 100P over 100 next to it. Cross out the 100p over 100 because it cancels out, then divide 465 by 100 and get $4.65.
Williams bill is $4.65