What is the square root of 64/25

Here's a thing you can do with square roots and fractions:

     √ (a/b)  =  √a / √b .    Is that neat or what !

So  √(64/25)  =  √64 / √25 .

We know the square root of  64  . . . that's  8 .
We know the square root of  25  . . . that's  5 .

So  √(64/25)  =  √64 / √25  =  8 / 5 .

But before we walk away from it, we need to remember that the
square root of any number can be either positive or negative. 
So both the '8' and the '5' can be either positive or negative.

When you mash that around, you realize that the question has
two answers.  They are . . .

     + 1.6  and  - 1.6 .

2x+10=36. x being the number of friends.