Question 540371
Let {{{ x }}} = liters of pure acid needed
given:
{{{ .2*5 = 1 }}} liter od pure acid in 20% solution
{{{ ( 1 + x ) / ( 5 + x ) = .6 }}}
{{{ 1 + x = .6*( 5 + x ) }}}
{{{ 1 + x  = 3 + .6x }}}
{{{ .4x = 2 }}}
{{{ x = 5 }}}
5 liters of pure acid is needed
check:
{{{ ( 1 + 5 ) / ( 5 + 5 ) = .6 }}}
{{{ 6 / 10 = .6 }}}
{{{ .6 = .6 }}}
OK
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I'm not sure how you did it, but this is how
I do all these kind of problems. Same answer.