Barium-141 and krypton-92 are produced by the bombardment of uranium-235 eith a neutron? 235 U 92 + 1 N 0 -->?

Write what you know. You know that Krypton-92 and Barium-141 are produced, so write them down already.

^{235}_{92} U + ^1_0 n \rightarrow \ ^{141}_{56} Ba + ^{92}_{36} Kr + ?

Count the number of protons and neutrons on either side of the equation. You'll see that there are 3 less neutrons. Well, those are the particles being produced, besides the energy released.

This becomes:

^{235}_{92} U + ^1_0 n \rightarrow \ ^{141}_{56} Ba + ^{92}_{36} Kr + 3 ^1_0 n