The sophomore class at Hoover High School has 118 girls. Of those girls, 64 play sports, 19 are on the debate team, and 4 belong to both. How many girls do not belong to either group?

The perimeter of △cde is 55 cm. a rhombus dmfn is inscribed in this triangle so that vertices m, f, and n lie on the sides cd , ce , and de respectively. find cd and de if cf=8 cm and ef=12 cm. the answer is not cd=20 and de=15. i have tried that one, it does not work.