I need a simple IF fromula.

[Bawth]

I'm having trouble with excel, so i have been watching training videos but i haven't figured out how to do a certain formula.
Ill, to the best i can, explain what I need help with. On my sheet i have three quarters(B5:D5), and i want the sum of all three, but with my third quarter(D5) if the value is equal or greater than 600 i want to add 10% (Which is my G3) to that value, but not the rest (B5, C5)

Thanks for taking the time and reading through my problem.

PS: Yes i know that there're 4 quarters, but i haven't reached the fourth quarter yet.

[etaf]

=if(D5>=600, B5+C5+(D5*1.1), sum(B5:D5) )
OR
=if( D5>=600, Sum(B5:D5)+G3, sum(B5:D5))

but with my third quarter(D5) if the value is equal or greater than 600 i want to add 10% (Which is my G3) to that value, but not the rest (B5, C5)

if you dont want B5 or C5 and so just D5+G3
then
=if( D5>=600, D5+G3, sum(B5:D5))