Example:

I have 2 adjacent columns of cells (A&B), each with thousands of different
values in them. I have a known value (C1) which also exists in one of the
cells of the range of values in (B). If, hypothetically, this value in C1
exists in B2304 I want a formula to give me the value in A2304.

In other words, D1 = Ax if Bx equals C1

Can someone please help me with this? )