Question

Solve the following equation:

$\frac{z}{z+15}=\frac{4}{9}$

Answer 1

Find the value of $z$

$$\begin{gathered} \frac{z}{z+15}=\frac{4}{9} \\ \Rightarrow 9z=4(z+15)[Crossmultiplication] \\ \Rightarrow 9z=4z+60 \end{gathered}$$

Rearranging the equation and combining like terms, we get

$$\begin{gathered} \Rightarrow 9z–4z=60 \\ \Rightarrow 5z=60 \\ \Rightarrow z=\frac{60}{5} \\ \Rightarrow z=12 \end{gathered}$$

Hence, $\mathit{z}\mathbf{}\mathbf{=}\mathbf{}\mathbf{12}$ is the solution of given equation.