A simple way to sum a result from UNION in MySQL

Question

I have a union of three tables (t1, t2, t3).
Each rerun exactly the same number of records, first column is id, second amount:

1  10
2  20
3  20

1  30
2  30
3  10

1  20
2  40
3  50

Is there a simple way in SQL to sum it up, i.e. to only get:

1   60
2   80
3   80

Answer 1

select id, sum(amount) from (
    select id,amount from table_1 union all
    select id,amount from table_2 union all
    select id,amount from table_3
) x group by id