The trick is to write appropriate equations and then solve the system of equations you've created.
"sum of two numbers is -5:" x + y = -5
"difference is -1:" x-y = -1
Add these two equations together. This will cause y to drop out, and you will be left with an equation in x alone:
2x = - 6, so x = -3. Subst. -3 for x in either equation, above, and find the corresponding y value.
Then write your solution as (-3, y ) (write in your value for y).
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:whats the question
Step-by-step explanation:question?
Answer:

Step-by-step explanation:
The information that we kow about the shape of the aquarium:
length:

width:

when the reef is submerged, the water level rises 3 feet. The volume that those 3 ft represent in the aquarium will be the volume of the reef.
Thus, we calculate the volume of water "addition" with the same length and width as the aquarium but with a deep of 3 feet (thi is because the reef caused the water to rise 3 feet), and this is the volume of the reef that was added to the aquarium:

The volume of the stone is 