Here are the two IF
expressions in your question:
If(X6>0; (((S7/V7)-($B$6))/$B$4)+$X$5; 0)
(with spaces added for clarity) and
IF(X6>10; $D$26=0; (((S7/V7)-($B$6))/$B$4)+$X$5)
I present them like this
because it’s not obvious from the question that the
(((S7/V7)-($B$6))/$B$4)+$X$5
subexpression is the same in both.†
Arjan’s answer is correct, but it depends on the fact that your two IF
expressions have a common subexpression.
I also wonder what you intend the $D$26=0
subexpression to do.
If it’s a typo, and you mean
IF(X6>10; 0 ; (((S7/V7)-($B$6))/$B$4)+$X$5)
then there’s another answer that (IMHO) is clearer:
IF(AND(X6>0;X6<=10); (((S7/V7)-($B$6))/$B$4)+$X$5; 0)
Note that your text says “between 10 and 0”,
but you are treating 0 and 10 differently.
____________
† By the way,
you can simplify this subexpression a little
by removing excess parentheses.
You can simplify it to any of the following:
(((S7/V7)-$B$6)/$B$4)+$X$5
((S7/V7-$B$6)/$B$4)+$X$5
(S7/V7-$B$6)/$B$4+$X$5