Letter analogy FJUL : BOQQ

F (-4) $\rightarrow$ B J (+5) $\rightarrow$ O U (-4) $\rightarrow$ Q L (+5) $\rightarrow$ Q

Applying the same pattern to LHRX: L (-4) $\rightarrow$ H H (+5) $\rightarrow$ M R (-4) $\rightarrow$ N X (+5) $\rightarrow$ C

Result: HMNC.