ah, those are systems you want one variable to cancel out. I would time the bottom equation by -1 so x cancels then u solve for y. then u plug all back in to solve for x.
8x - 33 = - 4x + 15
12x = 48
x = 4
Then substitute x back into a original equation to find y
y = (8x4) - 33
y = 32 - 33
y = - 1
So the answer is x=4 and y=-1
This problem is basically asking what 960x3.25 is, since 6 hours is one fourth of a day.
960x3.25=3120 watt-hours.
3120 watt-hours is your answer.
Step by step
(x - 21)(71)
=(x + - 21)(71)
=(x)(71) + (-21)(71)
=71x -1491
