Comparing 2 tabs on sheet to return a specific value in a specific cell

Sample Excel Template for formula.xlsI have 1 spreadsheet with 2 tabs.

When the UID in tab a and tab B are the same I would like to add the value of Big commit from Tab B to Big Commit to Tab A. It's possible Tab B will have more UID numbers than tab A.

I am having difficulty coming up with a formula.

Sample data:

Tab A

UID Small Commit Small Oblig Small Exp Big Commit Big Oblig Big Exp
123456c 10 8 8
124567b 13 7 5
123457d 6 5 2

Tab B

UID Big Commit Big Oblig BigExp
123457d 6 2 1
123456c 11 9 8
124567b 10 7 5