Using Raster calculator in Modelbuilder ArcGis 10

How do I use raster calculator in ArcGIS?

Click the toolset of interest to access the functional reference overview page for that group of tools. To access the Raster Calculator, select it from the Spatial Analyst toolbar menu. In the dialog box, you can enter Map Algebra in the expression box. The available rasters will be displayed in the Layers list.
 

How do I add a tool to ModelBuilder?

Type directly in ModelBuilder to open the Add Tools To Model dialog box and search for a specific tool. You can add a tool to the model by double-clicking it. You can also drag one or multiple tools from the search results. The Add Tools To Model dialog box includes all geoprocessing tools and model-specific tools.

How do you calculate raster area in ArcGIS?

Click the Source tab and note the cell size and linear units. Now just multiply the cellsize by the count to get the area in square units of whatever the linear units were.