OK, I have a mixing chart for oil/acrylic colors and the following combinations looked close on the chart. you will probably have to adjust the ratios for best results.
yellow --- 8 white, 1 yellow ochre, 1 spec ultramarine blue
olive green --- 2 white, 5 yellow ochre, 3 ultramarine blue
2 yellow ochre, 1 ultramarine blue
1 cadium yellow, 2 mauve
Red Brown --- 2 vermilloin, 1 ivory black
8 burnt umber, 8 alizarin crimson, 3 white
3 vermillion, 1 ivory black
There are three mixes for green and red-brown.
These are matched up to life color paints. These were eyeball matches using a color chart. Your mileage may vary.