I'm having trouble coming up with a formula to compare specific cells
in a row.

I have
A1 = TRUE
B1 = FALSE
C1 = FALSE
D1 = TRUE

and then
A3 = "R"
B3 = ""
C3 = "E"
D3 = "R"

I would like to have a TRUE/FALSE in column E representing the
evaluation of EXACT on that row; only comparing cells if Row 1 has a
TRUE in it.

Array entering =AND(EXACT(A3,A3:D3)) in D4 includes C3 and B3 in the
example above. How can I modify this formula?

Thanks