Hex #999888 or rgb(153,152,136) in RGB space is the tint of yellow. It has hue angle of 56.47 degrees, value = 60 and saturation = 11. #999888 can be obtained by mixing 4 colors: 1 drop of red, 1 drop of blue, 1 drop of green, 2 drops of white.
Nearest safe hex - #999999. Below you can see the block with #999888 color and its structure: in procentage ratio and in drops of pigments. Click "TRY" button to move #999888 to the mixer and play with it.