You put the scores in order from least to greatest, then you have to find the middle number. Now you will end up with two middle numbers you add them and divide by 2 then u have it answer.
You would first subtract 5*8 from 168 which would leave it at 128 then divided it by 8 and then you'll end up with 16 so each tree cost 16$

We know that
.
Solve using cross multiplication of the last two fractions. I will use
to represent the width of the rectangle. 
Multiply. 
Divide both sides of the equation by
. 
Carols age is 16
maxs age is 26
The slope of this would be 15