Question

Can someone help me solve A and B? I'm confused:(

Answer 1

p(a or b)= p(a)+p(b)-p(a and b)
0.7=0.6+p(b)-0.3
p(b)=0.4

p(a or b)= p(a)+p(b)-p(a and b)
=0.6+0.4-0.3
=0.7