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How much pure acid should be mixed with 6 gallons of a 20% acid solution in order to get a 90% acid solution?

beks73 [17]

So, how much acid is there in 6 gallons? well is 20% acid or (20/100), so the amount of acid in it just (20/100) * 6 or 1.2, the rest is say water.

now, if we want a 90% solution, and say we add "y" gallons, how much acid is in it? well (90/100) * y, or 0.9y.

now let's add "x" gallons of pure acid, now, pure acid is just pure acid, so is 100% acid, how much acid is there in it? (100/100) * x, or 1x or just x.

we know whatever "x" and "y" amounts are, they -> x + 6 = y

and we also know that x + 1.2 = 0.9y

$\bf \begin{array}{lccclll}
&\stackrel{gallons}{acid}&\stackrel{acid~\%}{quantity}&\stackrel{acid~gallons}{quantity}\\
&------&------&------\\
\textit{pure acid}&x&1.00&x\\
\textit{20\% sol'n}&6&0.20&1.2\\
------&------&------&------\\\
mixture&y&0.90&0.9y
\end{array}
\\\\\\
\begin{cases}
x+6=\boxed{y}\\
x+1.2=0.9y\\
----------\\
x+1.2=0.9\left( \boxed{x+6} \right)
\end{cases}
\\\\\\
x+1.2=0.9x+5.4\implies x-0.9x=5.4-1.2\implies 0.1x=4.2
\\\\\\
x=\cfrac{4.2}{0.1}\implies x=\stackrel{gallons}{42}$

3 0

3 years ago

Which could be the dimensions of a rectangular prism to service area is less than 160 ft.² check all that apply

raketka [301]

Area of rectangular prism is given by:

A=2(wl+hl+lw)

where w=width h=height, l=length

checking for given options

1. 8 ft, by 4ft by 3ft

Area = 136 square feet

5. 3 feet by 5 feet by 7 feet

Area =142 square feet

so our first and last option matches the requirement of area less than 160 square feet.

3 0

3 years ago

Read 2 more answers

Sam ran at 6km/h for two hours 20 minutes what distance did he run?

horrorfan [7]

He ran 14 km, multiply 6 by 2 and 1/3.

7 0

3 years ago

Macario is making 12 pounds of nut mixture with macadamia nuts and almonds. Macadamia nuts cost $9 per pound and almonds cost $5

Fynjy0 [20]

Marcario should use 4 pounds of macadamia nuts and 8 pounds of almonds.

Explanation

given

cost of macadamia nuts per pound=$9

cost of almond nuts per pound=$5.25

cost of the mixture per pound=$6.5

total pounds of the mixture to be made=12

let the pounds of macadamia nuts=x

pounds of almond nuts=y

total pounds of nuts=x+y=12

$x+y=12(1)\\9x+5.25y=6.5(x+y)\\\\9x+5.25y=6.5*12\\9x+5.25y=78(2)$

solving (1) and (2)

x=4

y=8

5 0

3 years ago

The length of the rectangle is 7/(x-4) feet, while its width is 5/x feet. Find its perimeter. Please help asap!!!!! :(

damaskus [11]

The perimeter would be (24x - 40)/(x^2 - 4x).

In order to find this, first double the length and width as you would to find any perimeter.

7/(x - 4) * 2 = 14/(x - 4)

5/x * 2 = 10/x

Now to add those together, we need to give them common denominators. In order to do that with the first one, we need to multiply by x/x

14/(x - 14) * x/x = 14x/(x^2 - 14x)

Then we can do the same with the second part by multiplying by (x - 4)/(x - 4)

10/x * (x - 4)/(x - 4) = (10x - 40)/(x^2 - 14x)

Now we can add the two together

14x/(x^2 - 14x) + (10x - 40)/(x^2 - 14x) = (24x - 40)/(x^2 - 14x)

3 0

3 years ago