The final velocity of Bill after he catches the pillow is 4.44 m/s.
The given parameters:
The final velocity of Bill is determined by applying the principle of conservation of linear momentum as follows;
[tex]m_1 u_1 + m_2 u_2 = v(m_1 + m_2)\\\\77(2.6) + 6.9(25) = v(77 + 6.9)\\\\372.7 = 83.9v\\\\v = \frac{372.7}{83.9} \\\\v = 4.44 \ m/s[/tex]
Thus, the final velocity of Bill after he catches the pillow is 4.44 m/s.
Learn more about conservation of linear momentum here: https://brainly.com/question/7538238