SOLUTION: ben is developing film in his darkroom when he realized he does not have the proper developer. he needs a mixture that is 20% developer, but he only has a mixture that is 80% devel

Question 48662: ben is developing film in his darkroom when he realized he does not have the proper developer. he needs a mixture that is 20% developer, but he only has a mixture that is 80% developer. how much pure water must be mixed with 9 pints of 80% developer to produce the mixture he needs. the answer is 27 but how do i write the equation.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
ben is developing film in his darkroom when he realized he does not have the proper developer. he needs a mixture that is 20% developer, but he only has a mixture that is 80% developer. how much pure water must be mixed with 9 pints of 80% developer to produce the mixture he needs. the answer is 27 but how do i write the equation.
-----------------------
80% developer DATA:
amount = 9 pints ; amount of active ingredient = 0.80(09)=7.2 pints
------------------------
0% water DATA:
amount = x pints ; amount of active ingredient = 0(x)=0 pints
-----------------------------
20% developer DATA:
amount = 9+x pints ; amount of active ingredient = 0.20(9+x)=1.8+0.2x pints
--------------------------
EQUATION:
active + active = active
7.2 + 0 = 1.8+0.2x
5.4=0.2x
x= 27 pints(amount of pure water he must add)
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Cheers,
Stan H.

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