Ok, so $\displaystyle P(A/R)=\frac{P(A \cap R)}{P\color{red}(R)}$

Plus $\displaystyle P(R/A)=\frac{P(A \cap R)}{P(A)} \Longleftrightarrow P(A \cap R)=P(R/A)P(A)$

Hence : $\displaystyle {\color{green} P(A/R)=\frac{P(R/A)P(A)}{P(R)}}$

I misread and $\displaystyle {\color{green} P(R/A)=.04}$, not $\displaystyle P(R \cap A)$

Let's calculate P(R).

$\displaystyle A \cup B=\Omega$

Hence :

$\displaystyle P(R)=P(R \cap A)+P(R \cap B)=\underbrace{P(R/A)}_{.04}$$\displaystyle P(A)+\underbrace{P(R/B)}_{.07} P(B)=.04*\frac{3}{4}+.07*\frac{1}{4}=.0475$

Then you can calculate P(A/R) now...

I hope I didn't make a mistake again