How to merge two Tables and Add the amount at the same time

Question

I have two Excel tables containing the frequency of each product and its unique identification. Although Table A contains every product identifier we currently have, Table B has much fewer, therefore the order is not precisely the same. Can a formula add the amounts for me, or at the least, write the values from table B into the relevant rows of table A?

Example:

Table A

A 10

B 10

C 10

D 10

E 10

Table B

A 10

C 10

E 10

Expected Result

A 20

B 10

C 20

D 10

E 20

Answer 1

Use SUMPRODUCT like this:

 =SUMPRODUCT(($A$2:$A$5=A10)*$B$2:$B$5)+SUMPRODUCT(($D$2:$D$4=A10)*$E$2:$E$4)