If a single letter is drawn from the set{m, a, t, h, e, i, c, s},what is the probability that the letter drawn is a member of the set {m,a,t,h}?

Cardinality (number of members) of the set

A : {m, a, t, h, e, i, c, s} = 8
Cardinality of the set B : {m,a,t,h} = 4
So the probability of drawing a single letter from A that is a member of B equals ?