Question 426151
Let {{{x}}} = pounds of $1.20/lb chocolate needed
(cost of chocolate) / (pounds of chocolate) = cost per pound
{{{ (1.2x + 10*.9) / (x + 10) = 1 }}}
{{{ 1.2x + 9 = x + 10 }}}
{{{ .2x = 1 }}}
{{{ x = 5 }}}
5 pounds are needed
check:
{{{ (1.2*5 + 10*.9) / (5 + 10) = 1 }}}
{{{ ( 6 + 9 ) / 15 = 1 }}}
{{{ 15/15 = 1 }}}
{{{ 15 = 15 }}}