The Fosters ordered a 20-inch diameter pizza for
dinner. The pizza contained 8 slides. Two slices
were left after the family ate dinner. What area of
the pizza is left?

answer:  

\boxed {\frac{1}{5}}  

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

solution-

60 *   \frac{1}{5}   = 12

90 * \frac{1}{5} = 18

75 * \frac{1}{5} = 15

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

hence, the answer would be \boxed {\frac{1}{5}}