Question 1183027
a) 
{{{D = RT}}} for {{{T}}}

{{{D/R = RT/R}}} 

{{{T=D/R }}} 


b) 

{{{A = P + Prt }}}for {{{r}}}

{{{A -P = Prt }}}

{{{A/Pt -P/Pt = Prt/Pt }}}

{{{A/Pt -P/Pt =r }}}

{{{r=A/Pt -1/t  }}}


c) 

{{{S = 4r^2}}} for {{{r}}}

{{{S/4=r^2}}}


{{{r=sqrt(S/4)}}}


{{{r=sqrt(S)/sqrt(4)}}}


{{{r=sqrt(S)/2}}}