P speaks truth in 70% of the cases.

Let A = Event that A speaks the truth
B = Event that B speaks the truth
Then, P(A) = 70/100 = 7/10
P(B) = 30/100 = 3/10
P(A-lie) = 1 - P(A) = 3/10
P(B-lie) = 1 - P(B) = 7/10
Now, A and B contradict each other = [A lies and B true] or [B true and B lies]
= P(A).P(B-lie) + P(A-lie).P(B)
= 7/10 × 7/10 + 3/10 × 3/10
= 49/100 + 9/100
= 58/100
= 58%