Let number=x
(X/2)+6=8
First subtract 6 on each side to isolate X on one side.
(X/2)=2
Now to fully isolate X by itself, just multiply 2 on each side.
X=4
4 pounds. if you divide the number of pounds by gallons you get the amount of pounds per gallon. 8 divided by 2 is 4.
We have no idea how 'x' responds to changes in 'y'.
We don't even know their units, to make a guess with.
-- If 'x' and 'y' are the ages of two people, then when y = 30, 'x' will be 23.
-- If they are the frequency and wavelength of a wave on the lake,
then when y = 30, 'x' will be 2 .
-- If 'x' is the weight of a rock in your front yard and 'y' is the number of pages
in today's newspaper, then 'y' has no effect on 'x'. No matter what happens
to 'y' . . . 'x' will always be 5 .
With the information given in the question, we just don't know.
We need either an equation, or else one more example.
You have to square the binomial.
(x^3 + 4y) (x^3 + 4y)
Using FOIL:
x^9 + 4(x^3)y + 4(x^3)y + 16y^2
x^9 + 8(x^3)y + 16y^2
You could also use the formula: (a+b)^2 = (a^2 + 2ab + b^2).
