5ncr3 plus 13ncr2 divided by 18ncr5

Answer 1

(5 choose 3) = 5*4 / 2 = 10

(13 choose 2) = 13 * 12 / 2 = 78

(18 choose 5) = (18*17*16*15*14) / (5*4*3*2)

= 18*17*16*14/(4*3*2) <-- 5 kills 15

= 3*17*16*13/ 4 <--- 3*2=6 which kills 18

= 3*17*4*13 <--- 4 kills 16

= 12*13*17

= 2652

(10+78) / 2652 = 88 / 2652 = 44/1326 = 22/663

the only factors of 22 = 2*11 so it cannot be reduced further because 663 does not divide by 11