Explanation
Before 4 pairs of socks were removed, the drawer contained 24 pairs of blue socks \((60 \times 40 \%=24)\) and 36 pairs of gray socks. (24+36 = 60). After removing 4 pairs of blue socks, the drawer contains 20 pairs of blue socks and 36 gray socks. Therefore, the ratio of gray pairs to blue pairs is 36 to 20, or 9 to 5.