Question 1035996
You need to know about combination http://betterexplained.com/articles/easy-permutations-and-combinations/

Here we have the option of either boys or girls. Therefore we have to add both options together.

for boys we have 14!/((14-2)!*2! = 91
for girls we have 17!/(17-2)!* 2! = 136

Now we have to add our two options together = 91+136