Assuming your 30 projects span from D3:DS3, try this formula:
=SUM($D$3:$DS$3*(MOD(COLUMN($D$3:$DS$3),4)=0)*$F$3:$DU$3*(MOD(COLUMN($F$3:$DU$3),4)=2))+
SUM($E$3:$DT$3*(MOD(COLUMN($E$3:$DT$3),4)=1)*$G$3:$DV$3*(MOD(COLUMN($G$3:$DV$3),4)=3))
You need to enter it as array formula, i.e. instead of pressing Enter at the end, press Ctrl-Shift-Enter!