Sum value of one column if in another column there is a text

Hello,


I am trying to sum values in column A if in column B there is a certain number.

So,

Column A
10
20
30
40
50

Column B
E45DISK
20D
P30POOL
P60TASK
45PROW

I wanna sum only those value of column A when in the respective row in column B there is the number 45. So, in this case, I wanna sum only 10 (E45DISK), 50 (45PROW). Can someon ehelp me with this? Thanks a lot, I tried in many ways but I can't figure out s solution