- The formula for converting Celsius (°C) to Fahrenheit (°F) is F = C 9/5 + 32. - To find the temperature where C = F, we set C = F = x. - The equation becomes x = x 9/5 + 32. - Rearranging the equation: x - (9/5)x = 32 => (5x - 9x)/5 = 32 => -4x/5 = 32. - Multiplying by 5: -4x = 160. - Dividing by -4: x = -40.