15-9+6+3 =? What's the answer of this?

Scientific evidence tells us that the cause of earths four season is the tilt of earth as it revolves around the sun. the student is instructed to illustrate this information in a science notebook. how will the student illiterate winter in the northern hemisphere?

Achemist has dissolved a certain substance in water. the chemist knows that more of the substance could be dissolved into the water before it stops dissolving. therefore

8) warming your hands by a fire is an example if which heat transfer? a. conduction b. convection c. radiation d. none of these