VBA Code to add a value from one cell to the contents of another cell

[Elshami]

I need vba code which will go to a certain cell that contains a groub of summation numbers and add another number from another cell ( value or formula) to them. So, for example: In cell "A1", "10" ( result from ("D1"+"G1") I need to add it to "B1" wich contain "=7+8+9" to become "=7+8+9+10", the next day the value of "A1" , "11",again "B1" become "=7+8+9+10+11" and so on. "B1" appear in excel sheet "34", "45" Respectively.Is that possible?