I need function that gives grades for example :
A student who got 8 / 6,1 / 8 / 7 / -
the - means that the student misses the exam but has a valid excuse, so this exam will not be count, also we should take care of that each exam has weightening factor.
C14 = 8
D14 = 6,1
E14 = 8
F14 = 7
G14 = -

the weightening factors
C15 = 1
D15 = 2
E15 = 1
F15 = 2
G15 = 1

Thankssss

also the function has to make it able for us that if we add a new row it counts this row too.