Can I mix a latex flat apint with an acrylic semi gloss paint?

Of the two paints you are going to try mixing, a water based paint (latex), with a spirit based (possibly methalated) . Not a good idea as they will separate. DO NOT MIX! On the containers for these paints you will be told how to wash your brushes ie.. Water for Latex. Turpintine, or Varsol for the Oil based paints and stains. Again, Oil and Water do NOT MIX!!!