Question 329066
Choose 6 from the 15 boys and 4 from the 9 girls. 

{{{C(15,6)*C(9,4)=630630}}}

Do you have a calculator that does combinations and permutations?. Many calculators do these operations. It is easier than working through the formula.

{{{C(15,6)=15!/(6!9!)=5005}}}

Example:

If we write this out and cancel the appropriate terms, we get:

{{{15*14*13*12*11*10*9*8*7*6*5*4*3*2/((6*5*4*3*2)*(9*8*7*6*5*4*3*2))}}}

Cancelling, it whittles down to:

{{{5*7*13*11=5005}}}