Question

If P(A or B) = 0.7, P(A) = 0.3 and P(B) = 0.8, determine P(A and B).
0.21
0.56
0.10
or
0.40

Answer 1

\[P(A \cup B)=P(A)+P(B)-P(A\cap B)\] you know every number but
\[P(A\cap B) so you can solve for it.
is that ok?