You are lucky, I am having a test on these tomorrow. (at the time I posted this)
first, use a magnet to separate the iron fillings. Technically called "hand separation"
ps, using a electromagnet may be better as u can cut out the electricity and the iron fillings will fall.
second, sand and salt left, dissolve them in water, then filtrate it. Technically called "filtration"
sand and salt solution left
third, distil or evaporate the water, so that salt is left over. Technically called "distillation" and "evaporation".
All three substances are separated, aren't they?