Question 747587
Your equation is correct.
{{{pi*x^2=((x+9)/2)*pi*x}}}
Dividing both sides of the equal sign by {{{pi*x}}}, and then multiplying both sides times 2, we get
{{{pi*x^2=((x+9)/2)*pi*x}}} --> {{{x=(x+9)/2}}} --> {{{2x=x+9}}}
Then subtracting x from both sides, we get
{{{2x=x+9}}} --> {{{highlight(x=9)}}}