I\'m sorry if this question seems \"noobish\" but I can\'t figure it out

I have 2 tables

we will call them table1 and table2

I use this query

SELECT 1.blah, 2.id, 1.number FROM table1 1, table2 2 WHERE 2.id = "X" AND 1.blah = "X"------------------------

id - blah - number

----------------------

X - X - 3.00

X - X - 4.00

X - X - 7.00

X - X - 4.00

I would like to add all of the numbers to give me one value I can use

can anyone help?

thank you