Mathematics
posted by Sarah on .
1. make p the subject:
p/p3= R
2. make R the subject
a= 1 1/R

You must mean
p/(p3) = R
crossmultiply
Rp  3R = p
Rp  p = 3R
p(R1) = 3R
p = 3R/(R1)
for the second, multiply each term by R, rearrange and factor in a similar way.
Let me know what you get. 
So for the second one, I multiplied each term by R
aR= R 1
but then I got stuck after that... sorry 
you are looking for R, so get the R's to one side
aR  R = 1
factor out the R
R(a1) = 1
divide both sides by a1
R = 1/(a1)