The answer is D. $780.25
In this particular case, you just need to find the difference between what Casey earn hourly with his total earning..
The hourly wage that Casey earned in 26 hours:
$ 4.55 x 26 = 118.3
The total amount that casey earned in 26 hours:
$898.55
So, the amount that Casey earned through tips:
$898.55 - $118.3 = $780.25