Question 913696
The wording is VERY confusing, and I have done
many, many of this exact type of problem- nuf said
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{{{ 820*.16 = 131.2 }}} = pounds of tin in 16% alloy
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Let {{{ x }}} = pounds of pure tin to be added
{{{ ( 131.2 + x ) / ( 820 + x ) = .18 }}}
{{{ 131.2 + x = .18*( 820 + x ) }}}
{{{ 131.2 + x = 147.6 + .18x }}}
{{{ .82x = 147.6 - 131.2 }}}
{{{ .82x = 16.4 }}}
{{{ x = 20 }}}
20 pounds of tin must be added to
the 16% alloy
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check:
{{{ ( 131.2 + x ) / ( 820 + x ) = .18 }}}
{{{ ( 131.2 + 20 ) / ( 820 + 20 ) = .18 }}}
{{{ 151.2 / 840 = .18 }}}
{{{ 151.2 = 151.2 }}}
OK