Start with your given equation - F=9/5C+32
Subtract 32 from both sides - F-32=(9/5) degrees C
Multiply both sides by 5 - 5(F-32)=9C
Divide both sides by 9 to isolate C - (5/9)(F-32)=C
Answer - C=(5/9)(F-32)
I AM NOOO MATH EXPERT, BUT THAT IS WHAT I GOT... HOPE THIS HELPS!