According to the balanced equation of this reaction :
2HBr(g) → H2(g) + Br2(g)
when we have the coefficient of the reactant is 2 and when the rate of disappearance is 0.19 m,
So the rate of appearance = the rate of disappearance^(the coefficient of the reactant)
= 0.19^2
=0.0361 m.S^-1