The alignment is a bit out in your posting. Assume headings are in row
1, with Items in column A, 50 in cell B1, 70 in C1 and 1.5 in D1. In E2
type in this array formula*:

=SUM(IF(B2:D2<0,B2:D2/B$1:D$1*2.5,0))

*As this is an array formula, when you have entered it (or subsequently
edit it) you must use CTRL-SHIFT-ENTER instead of ENTER. If you do this
correctly, then Excel will wrap curly braces { } around the formula -
you must not type these yourself.

Copy the formula down column E for as many rows as you have items.

Hope this helps.

Pete