Question 332968
Let {{{x}}} = number of solid-color ones sold
Then {{{40 - x}}} = number of print ones sold
given:
Sales of solid-color ones = {{{9.9x}}}
Sales of print ones sold = {{{12.75*(40 - x)}}}
{{{9.9x + 12.75*(40 - x) = 421.65}}}
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{{{9.9x + 510 - 12.75x = 421.65}}}
{{{-2.85x = -88.35}}}
{{{x = 31}}}
{{{40 - x = 40 - 31}}}
{{{40 - 31 = 9}}}
31 solid-color ones and 9 print ones were sold
check:
{{{9.9x + 12.75*(40 - x) = 421.65}}}
{{{9.9*31 + 12.75*(40 - 31) = 421.65}}}
{{{306.9 + 114.75 = 421.65}}}
{{{421.65 = 421.65}}}
OK