Determine how much of a tip is added if ther is a party of 15 and the total bill is 248

Question and answers are in the attached picture. you so much in advance.

Dexter read 11 science fiction books and 5 history books. lena read 9 science fiction books and 4 history books. compare the students’ ratios of science fiction books to history books. 1. determine the ratios’ form:    science fiction books to history books 2. write the ratios as fractions:    dexter: 115; lena: 94 3. rewrite with a common denominator. 4. compare. 5. answer the question. determine which shows the correct comparison of the ratios for this problem.

If f(x)=x+7 and g(x)=1/x what is (fog)(x)