Education gap

An article about a miracle gadget for keeping your feet warm in bed said it makes your feet 3.5 deg.C warmer or 38 deg.F. What!! Cobblers.
    Consult an expert: my housekeeper’s daughter got an A in her physics O-Level. She reminded me that to convert from Centigrade to Fahrenheit, you divide by 5 and multiply by 9. Which made the rise 6.3 deg.F.
    So where does the 38 come from? A room temperature of 3.5 deg.C is the equivalent of 38.3 deg.F because 0 deg.C = 32 deg.F.
    I bet the hack who wrote the article got an F in his physics O-Level.