jitu_foo.rb

class Fixnum
  def is_prime?
    2.upto(self-1).none? do |y|
      self%y==0
    end
  end

  def prime_factors
    2.upto(self).select do |x|
      self%x==0 && x.is_prime?
    end
  end
end

def can_she_equalise? a,xyz
  pf=a.map(&:prime_factors)
  result=((pf.flatten-pf.reduce(&:&))-xyz).empty?
  result ? "She can" : "She can't"
end

puts can_she_equalise?([2,4],[2])
puts can_she_equalise?([2,6,7],[2,3])
puts can_she_equalise?([49,98],[2])