Simple maths equation. Help needed ASAP please

Thanks heaps!!

Greatly appreciated!

:)

x+9 over x-4 equals 7 over 9 What does x equal ?

$\begin{array}{rcll} \frac{x+9}{x-4} &=& \frac79 \qquad & &| \qquad\cdot 9\\\\ 9\cdot \left( \frac{x+9}{x-4} \right) &=& 7 \qquad & &| \qquad\cdot (x-4)\\\\ 9\cdot(x+9) &=& 7\cdot (x-4) \\\\ 9x + 9\cdot 9 &=& 7x - 7\cdot 4 \\ 9x + 81 &=& 7x - 28 \qquad & &| \qquad -7x \\ 9x -7x + 81 &=& - 28 \\ 2x + 81 &=& - 28 \qquad & &| \qquad -81 \\ 2x &=& - 28 -81 \\ 2x &=& -109 \qquad & &| \qquad :2 \\ x &=& -\frac{109}{ 2 }\\ \mathbf{x} &\mathbf{=}& \mathbf{-54.5}\\ \end{array}$