The given equation is :
[tex]R = 5(\frac{c}{a} -0.3)[/tex]
Divide both sides by 5
[tex]\frac{R}{5} =\frac{c}{a} -0.3[/tex]
Add 0.3 to both sides.
[tex]\frac{R}{5} +0.3=\frac{c}{a}[/tex]
Multiply a on both sides.
[tex]a(\frac{R}{5}+0.3)= c[/tex]
Hence [tex]c= a(\frac{R}{5} +0.3)[/tex] ... Answer