Question

How do you solve $A=P+Prt$ for $r$ ?

Answer 1

Separate the $r$ term from other terms in the expression:

Given expression is $A=P+Prt$

Write $r$ in other terms $A$, $P$ and $t$.

$P+Prt=A$

Subtract both sides by $P$.

$$\begin{gathered} \therefore P+Prt-P=A-P \\ \Rightarrow Prt=A-P \end{gathered}$$

Divide both sides by $P$ and $t$ to separate the term $r$.

$$\begin{gathered} \therefore \frac{Prt}{Pt}=\frac{A-P}{\left(Pt\right)} \\ \Rightarrow r=\frac{A-P}{\left(Pt\right)} \end{gathered}$$

Hence, the value of $r$ is $\frac{A-P}{\left(Pt\right)}$.