Formula to Determine Reorder Point

[cobraman]

Hello,
I am attempting to determine the best date to reorder goods based on a number of interchangeable data (number of transit days, min value of safety stock). The formula result i would like is for B21 to correspond to a date in row 1. The date "trigger" would be when a value within the array of row 9 are < B19+(B20*B23), though i cannot figure out a solution that would give me the corresponding date. the solution to B22 would simply be B21+B23, though this does not work without B21 having a legitimate answer. Any help our guidance would be greatly appreciated.

[mehmetcik]

Formula for B20 =AVERAGE(OFFSET(C4,0,0,1, MATCH(99^99,4:4)))

Formula for B21 =INDEX(1:1,1,MIN(MATCH(B20+B20*B23,9:9,-1),MATCH(0,9:9,-1)-12))

Formula for B22 =SUBSTITUTE(B21,".","/")+B23

Custom Format for B22 = dd.mm.yyyy