If by page, you mean worksheets, in destination sheet (in your case 3rd page)
enter "=" and then click the sheet tab at the buttom and click the desired
cell. when you finished referencing your cells in this manner, click enter.
Now if you look to the cell you have entered the formula, you can see the
sheet name before cell references separated by a "!", which means it has
brought the parameteres from those sheet.
In this manner you can reference any cell from the same workbook and even
from other workbooks (Excel files)
HTH