1220/9.35 = 130.4 hours
$ he needs - $ he has:
5100 - 1220 = 3,880
The $ he still need/$he gets paid per hour:
3,880/9.35 =414.9
He will need to work 415 more hours.
130 + 415 = 545 total hours
** I don’t understand if you need to get how many more hours he needs to work or the full total of hours.