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20days louise can read300 pg

step-by-step explanation:

1 day 15 pg 300: 15= 20

x day 300 pg

the answer for the second equation is (4,0)

here is something that relies on definition of subset and logical implication:

the definition of a subset is that if there are two sets a and b of a certain universe, a is a subset of b if every element in a is also an element of b, i.e.

  for all x, if x ∈ a, then x ∈ b

the empty set ∅ has no elements, so if a is any set from any universe, then ∅ ⊆ a (∅ is a subset of a) is true if

  for all x, if x ∈ ∅, then x ∈ a

clearly, x ∈ ∅ is always false because the empty set has no elements. so this implication is always true (remember that logical implication is only false if a true premise implies a false conclusion), thus making ∅ ⊆ a always true.