The striton family had a meal catered for a wedding rehearsal dinner. the cost of the dinner was $476. there was a 5% sales tax and they left a 15% tip. what was the total cost including the sales tax and the tip.

5% of 476 =0.05*476
1) If the tips were left from the cost of dinner including sale taxes
15 % tips would be (476+0.05*476)*0.15.
2) If tips would be left only from the cost of the dinner it would be 
0.15*476

Total cost = cost of dinner +tax+tips
1)    for the case when tips left from the sum of cost of the dinner and taxes
 total cost = 476 +0.05*476 +  (476+0.05*476)*0.15=574.77

2) for case when tips left only from the cost of the dinner
total cost = 476 +0.05*476 +0.15*476 = 571.20

Usually, tips are given from the cost + taxes,
so maybe you need choose route 1).

What exactly is your question?