144 ounces! There are 8 ounces in 1 cup. 8x18= 144!! :D
You add two equations together to eliminate a variable. This particular problem is nice, because it's already setup to eliminate X.
3x - 4y = 9
<span>-3x + 2y = 9
</span>
When we add these two together, 3x - 3x cancels each other out, leaving us with 0x, or nothing.
We continue with -4y + 2y (leaves us with -2y) and 9+9 (18).
-2y = 18
18/-2 = -9.
Now we have y = -9, and we can go back into the problems to solve for x.
<span>3x - 4(-9) = 9
</span>
3x + 36 = 9.
3x = -27
x = -9.
Confirm with the final equation:
-3(-9) + 2(-9) = 9
27 - 18 = 9
9 = 9 --- Confirmed.
-(5y) - y = 18
-6y = 18
y = -3
x = 5(-3)
x = -15
(-15, -3)
5x + 4(-7x - 3) = -35
5x -28x -12 = -35
-23x = -23
x = 1
y = -7(1) - 3
y = -10
(1,-10)
the answer should be C. 5.27
Keep in mind the the word "percent" translates to "for each 100." 25% can be read as "25 for each 100," which has the fractional representation

and the decimal representation 0.25. All of these representations are just different ways of writing the same value.
Note too that the fraction

can be reduced to

, so what the question is really asking is: 1/4 of what number is 9?
Well, if we know that 1/4 of the number is 9, we can easily find how large the whole number is by finding all 4/4 of it (the <em>whole</em> number)<em /><em />, or 4 x 9, which multiplies out to
36.