Question 988084
{{{S(x)=D(x)}}}
{{{300x+9000=-100x+14000}}}
{{{400x=5000}}}
{{{x=5000/400}}}
{{{x=25/2}}}
{{{x=12.50}}}
Then,
{{{y=300(12.5)+9000}}}
{{{y=12750}}}