"Darryl" wrote:
If A17 = horiz curve and C17 = 90 then answer
should return what is in C10, but if A17 = horiz curve
and C17 = 45 then answer should return = C11
how do I write a formula for this?

That depends. What result do you want when those conditions are not met;
that is, when you would not get C10 or C11?

The following results in a null string ("") in that case.

=if(A17<"horiz curve", "",
if(C17=90, C10, if(C17=45, C11, "")))