11.

. [Number Theory, 5 Points] Two integers are relatively prime if there is no integer greater than one that divides them both. For example, 12 and 13 are relatively prime, but 12 and 14 are not. Which of the following couples are relatively prime numbers? A) 15 and 85 B) 49 and 64 C) 21 and 56 D) 15 and 81 E) 23 and 69 . [Combinatorics, 5 Points] What is the maximum number of points of intersection of 6 distinct lines, if only two of them are parallel lines? A) 15 B) 14 C) 13 D) 12 E) 11. [Algebra, 7 Points] In a math club there are 18 boys and 28 girls. Every week 4 more boys and 3 more girls join the club. In how many weeks will the number of boys and the girls in this club be the same? A)? B)8 (3)9 D)1O E)11