Question 4398
First of all: The formula you stated is not quite right. F=(9/5)C+32 (not +2)
Now, solving this formula for C you have to first divide both sides by 9/5. The rule says that dividing by a fraction you multiply by its reciprocal which is 5/9. Thus:
F*(5/9)= C+32*(9/5)*(5/9) 
F(5/9)= C+32 Now substract 32 from both sides
F-32(5/9) = C+32-32
Your final formula is:
C=(5/9)F-32