Someone give me the answer this equation!

D. (5,-4)
you can eliminate the 5x and -5x because they are opposites
Then you add the two equations together
you get -9y = 36
solve for y and you get -4
plug -4 into one of the original equations
Ex. 5x+3 (-4)=13
Solve for x
you get 5x = 25
then you finish solving and get x=5

The answer should be D. (5,-4) the x’s cancel each other out then add 3 and -12 which is -9 and add 13+23 and you’ll get 36 so the equation will be -9y=36 then divide by 9 then to get x plug -4 in for the y

Workdone = 4900joules

Step-by-step explanation:

Work-done = force x distance

Force = mass x acceleration

If we suppose that the aquarium is at height 0 at the top and height 1 at the bottom (since it's 1m deep), then we need to lift the slide at height x by x metres.

Mass = Density x Volume, therefore force needed to lift the slice is given is

F = density*volume*∆x*acceleration

Since we the mass changes as we take out water then there will be a change in height, for this reason we have ∆x.

Acceleration is due to gravity, therefore g=9.8m/s²

Density = 1000kg/m³

Volume = 4*1*1 = 4m³

F = 1000*4*∆x*9.8 = 39200∆x

Since our distance from the top of the aquarium to the bottom is x metres, then

Work-done = 39200x∆x

To find the total workdone, we find the integral of 39200xdx and the limit will be from 0 to 0.5 since we are to pump halfway of the aquarium. Integrating that we have

19600*x² limit from 0 to 0.5

19600(0.5² – 0²) = 19600(0.25 – 0) = 19600(0.25) = 4900joules