=A1*LOOKUP(B1,{"D","T","";1.5,8,2})

"Pipeline welder" wrote:

I am using Excel 2007
A1=8

B1, requires an input in letter form, such as "D" or "T" or it is left empty

C1, would be the product of A1*2, if B1=D OR A1*1.5, if B1=T OR C1 would be
8 if B1 were left empty