Question 773181
n C r = (n!)/(r!(n-r)!)


15 C 7 = (15!)/(7!*(15-7)!)


15 C 7 = (15!)/(7!*8!)


15 C 7 = (15*14*13*12*11*10*9*8!)/(7!*8!)


15 C 7 = (15*14*13*12*11*10*9)/(7!)


15 C 7 = (15*14*13*12*11*10*9)/(7*6*5*4*3*2*1)


15 C 7 = (32432400)/(5040)


15 C 7 = 6435



Answer: 6435