When simplified, y=2(x+4)+5 equals y=2x+13
Remark
Many calculators have a key that will do this in one step. Mine is one of them. So let's start with the answer and then we'll do it the long way.
9C3 = 84. You put it into your calculator as 9 2nF nCr 3 =
Solution

3*4*7 = 84 which is what you set out to show.
I’m not entirely sure, but try Desmos or Symbolab calculators :)
8. It is divisible by both 32 and 40.