Answer
[tex]\begin{gathered} \text{Given relation: A }=P+\frac{PRT}{100} \\ \text{Multiply both sides by100} \\ 100A=100P+100(\frac{PRT}{100}) \\ 100A=100P+\text{PRT} \\ 100P+\text{PRT}=100A \\ P(100+RT)=100A \\ \text{Divide both sides by (100+RT)} \\ P=\frac{100A}{100+RT} \end{gathered}[/tex]