00:01
Looking at a family where each daughter has the same number of brothers as she has sisters.
00:05
Each son has twice as many sisters as he has brothers.
00:09
Okay, so when you have a word problem like this, you have two options.
00:12
You can do trial and error, or you can try and turn it into an algebra problem.
00:17
So let's do that.
00:20
Turn it into algebra.
00:26
So let's have x equals the number of daughters, and y equals the number of sons.
00:35
Okay, so each daughter has the same number of brothers as she has sisters.
00:41
So her number of brothers is going to be however many sons there are, and her number of sisters will be x minus 1, because she isn't her own sister, but every other daughter is her sister.
00:53
Next, each son has twice as many sisters as he has brothers...