$\"\"$

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(a)

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A tank contains $\"\"$ of brine with $\"\"$ of dissolved salt.

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Pure water enters the tank at a rate of $\"\"$ .

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The solution drains from the tank at the rate of $\"\"$ .

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Change in salt concentration of salt $\"\"$ is the salt coming into the tank minus the salt going out of the tank.

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Salt coming into the tank is $\"\"$ .

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Salt going out of the tank is $\"\"$ .

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Change in salt concentration of salt is

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$\"\"$

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Apply integration on each side.

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$\"\"$

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Apply exponent on each side.

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$\"\"$

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The initial concentration of salt is $\"\"$ , where $\"\"$ .

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$\"\"$

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Substitute $\"\"$ in $\"\"$ .

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The concentration of salt after $\"\"$ minutes is $\"\"$ .

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$\"\"$

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(b)

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Find the concentration of salt after $\"\"$ minutes.

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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The concentration of salt after $\"\"$ minutes is $\"\"$ .

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$\"\"$

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(a) The concentration of salt after $\"\"$ minutes is $\"\"$ .

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(b) The concentration of salt after $\"\"$ minutes is $\"\"$ .