Translate the following inference to logic notation: If it is windy, then David is playing squash. David is climbing a mountain if and only if it is windy. For all x, if x_17 plays squash, then x_17 is climbing a mountain. Therefore if it is windy, then David is climbing a mountain.
p -> P(a). Q(a) <-> p. forall x: P(x) -> Q(x). Therefore p -> Q(a).