Answer: 1 brain
Step-by-step explanation:
If one person has a brain, the number of brains they have, x, is 1.
Then, upon giving a brain to another person, x decreases by 1, becoming 0.
Then, when given a brain, x increases by 1, settling at 0.
Hope it helps :)

Answer:
The cost to rent a bike
Step-by-step explanation:
Answer: The range is 
Explanation:
The parabola opens down, forming a "frowny face" in a way (just without the eyes). Or you can think of it as a hill or mountain. This means that the vertex (-3,-6) is at the top of that mountain. It's the highest point of that parabola.
The range is the set of all possible y values. We see that y = -6 is the largest it can get. So y = -6 or y is smaller than this. We would then write
to describe all the possible y values.
Therefore, the range is 
This translates to "y is a real number such that y is -6 or smaller".
So the second answer you wrote is close, but you forgot the "or equal to" portion of the inequality sign.
See below for a visual example of what's going on.
Answer:
x = 32
Step-by-step explanation:
This is an equilateral triangle, all three sides equal. Since all three sides are equal, all three angle are equal. 180/3 = 60. That means each angle is equal to 60 degrees.
2x-4 = 60
Add 4 to each side
2x-4+4 = 60+4
2x =64
Divide each side by 2.
2x/2 = 64/2
x = 32