Average on percentage but with different weightings

[Riaang]

Good day. I'm busy with performance reviews for staff but are battling with the following.

Section 1 for instance gives me an achieved percentage of 80% and the weighting for this section is 50.
Section 2 has a achieved percentage of 40% but the weighting for this section is only 30.
Section 3 has a achieved percentage of 60% but the weighting for this section is only 20.

I need to calculate the average percentage for the 3 sections together but I can't use 80% + 40% + 60% devide by 3 because the weighting for the 3 sections are not the same.

Can someone please help me in how I will get the average percentage for the 3 sections combined but taking in consideration the weighting.

Kind Regards

 

[Sulprobil]

=80%*50%+40%*30%+60%*20%

=64%