Answer:
Step-by-step explanation:
Let's try guessing...
All the units place has to be 4, if it is higher than 4 then the answer will not be 90 (the sum of the four rounded numbers).
Going off the idea that this is 4/(y+2) - 9/(y-2) = 9/(y^2-4), let's first rewrite y^2-4 in the form of a^2-b^2, where a=y and b=2.
y/(y+2)-9/(y-2)=9/(y^2-2^2)
Now, use difference of squares: a^2-b^2=(a+b)(a-b)
4/(y+2)-9/(y-2)=9/((y+2)(y-2))
Multiply both sides by the Least Common Denominator: (y+2)(y-2)
4(y-2)-9(y+2)=9
Then keep on simplifying until you get your answer
-5y-26=9
-5y=9+26
-5y=35
y=35/-5
y=-7
Yay! Our answer is y=-7!
Answer:
the amount you owe, and how much energy you have used
