1. The problem is to convert 50° Fahrenheit (F) to degrees Celsius (C). 2. The formula to convert Fahrenheit to Celsius is: $$ C = \frac{5}{9} (F - 32) $$ 3. Substitute $F = 50$ into the formula: $$ C = \frac{5}{9} (50 - 32) $$ 4. Calculate inside the parentheses: $$ 50 - 32 = 18 $$ 5. Multiply by $\frac{5}{9}$: $$ C = \frac{5}{9} \times 18 $$ 6. Simplify the multiplication: $$ C = 5 \times 2 = 10 $$ 7. Therefore, 50° F is equal to 10° C. The correct answer is a) 10° C.