Probability

The even numbers are 2, 4 and 6 — three outcomes out of six equally likely ones, so $\tfrac36 = \tfrac12$.

The complement is $1 - P(A) = 1 - 0.3 = 0.7$.

There are 36 equally likely ordered outcomes. Six of them give 7: $(1,6),(2,5),(3,4),(4,3),(5,2),(6,1)$. So $\tfrac{6}{36} = \tfrac16$.

Mutually exclusive means $P(A \cap B) = 0$, so nothing is subtracted: $0.6 + 0.3 = 0.9$.

$\dfrac58 \times \dfrac47 = \dfrac{20}{56} = \dfrac{5}{14}$. Both the numerator and the denominator fall by one on the second draw.

Two paths: $\dfrac58 \times \dfrac37 = \dfrac{15}{56}$ and $\dfrac38 \times \dfrac57 = \dfrac{15}{56}$. Adding gives $\dfrac{30}{56} = \dfrac{15}{28}$.