Using Numbers for personal expenses

Question

Hi, I want to make an expense and debt tracking spreadsheet in Numbers for my iPhone.  I would use iCloud to keep it up to date, and look at more detailed reports and bigger tables on my iPad and desktop iMac.
So, my plan is to have one page for entry of daily expenses.  This would be a simple page so I can see it clearly on my iPhone.  I would make a new sheet at the beginning of every month.  Let's call this Table A.  It would be a table with three columns: 1) today's date, 2) the category of expense, and 3) a column for amount.  The "category of expense" column would have a pop-up menu with preset lists of expense types (Rent, groceries, electric bill, etc).  I would add a new row for each time I spend money.
All other tables would be bigger and more complicated, too big to see on an iPhone comfortably, so they would be on different sheets.  Here's what I want to do:
1. First, I want to keep a table (call it Table B) that lists a sum of all the money I spent this month so far divided by category: the sum of all the amounts I entered for groceries, the sum of all the amounts I entered for gas, etc.  Table B column 1 would simply be the name of the category (gas, groceries, electric bill, etc) and column 2 would be the sum of all that month's expenditures in that category. 
So column B has to have a function that can read all the values in Table A column 3 (amount) and be able to identify which entries are in which category.  Is there a function that can sum up the amounts in column 3, but only the ones that are identified in a particular category in column 2?  The current spreadsheet I use on my iMac just has a huge table with rows for dates and columns for categories, but it's too big to look at on my iPhone.
2. Getting back to Table B, I want another sheet that keeps a list of all the amounts categorized by month, by category.  Each column would replicate Table B column 2 from each month's sheet (I would also have a line graph associated with this table).  When I make a new sheet for each month, and a new column on this table for each month, is there some way to automate it so I don't have to make a new function each time?
Thanks for your help with this, I've been able to figure out all the functions I need expect for these few things.  Any help would be appreciated.

Answer 1

I think my problem is that I have inadvertently created three tables (I only want one). I have included a screen shot of the light grey line under B and the words Table 1 behind it.