If P denotes ‘+’, Q denotes ‘–’, R denotes ‘÷’, S denotes ‘×’ and 28P8R4Q3S1= a³, then the value of "a" is

​28P8R4Q3S1= a³

​$$\begin{array}{|c|c|} \hline\textbf{Operation preference wise} & \textbf{Symbol} \\\hline\text{Brackets} &[], {}, () \\ \hline \text{Orders, of} & (power), √ (root) , of \\ \hline \text{Division}& ÷ \\ \hline \text{Multiplication} & × \\\hline \text{Addition} &+ \\ \hline \text{Subtraction} & - \\\hline\end{array}$$​​

So the expression becomes:

28 + 2 – 3 × 1 = a³

28 + 2 – 3 = a³

30 – 3 = a³

27 = a³

The value of the expression is 27, and we’re told that it equals a³, which means:

a³ = 27

So, a = 3 $$\rightarrow$$​ (3)³= 27

Thus, the correct option is: (b)