Logarithms & non linear data

[cerulean finch]

Is the gradient for 6c wrong on the ms? i'm doing this...

[cerulean finch]

my calculations

log(f)=log(AR^b)
log(f)=logA+logR^b
log(f)=blogR+logA

y=mX+c

m=b
c=logA
b=-0.75 / -0.8 (to 1 d.p)