The buffet cost for Mr. Smith and his wife is $30 x 2 = $<<30*2=60>>60.
The buffet cost for his children is $15 x 3 = $<<15*3=45>>45.
The buffet cost for 1 senior citizen is $30 x 90% = $<<30*90*.01=27>>27.
B
uffet cost for the grandparents is $27 x 2 = $<<27*2=54>>54.
Buffet cost for the entire family is $60 + $45 + $54 = $<<60+45+54=159>>159
#### 159