Oliver has 10 $20 and 3 $5 bills. William has 15 $10 and 4 $5 bills. How much more money does Oliver have than William? Let's be accurate as possible.
Oliver's $20 bills amount to $20 x 10 = $200. Oliver's $5 bills amount to $5 x 3 = $15. So, Oliver has a total of $200 + $15 = $215. William's $10 bills amount to $10 x 15 = $150. William's $5 bills amount to $5 x 4 = $20. So, William has a total of $150 + $20 = $170. Therefore, Oliver has $215 - $170 = $45 more than William.
The answer: 45.