To find the number of women in the workforce in 2020 using the given function \( P = 0.79x + 20.86 \), we first need to determine the value of \( x \) for the year 2020.
Since \( x \) represents the number of years after 1950, we calculate:
\[ x = 2020 - 1950 = 70 \]
Now, we can substitute \( x = 70 \) into the function to find \( P \):
\[ P = 0.79(70) + 20.86 \]
Calculating \( 0.79 \times 70 \):
\[ 0.79 \times 70 = 55.3 \]
Now, substituting back into the equation:
\[ P = 55.3 + 20.86 = 76.16 \]
Thus, the number of women in the workforce in 2020 is approximately \( 76.16 \) million.
Therefore, the answer is:
76.16 million