Rename Problem to Translation

app/models/translation.rb

@@ -0,0 +1,10 @@
+class Translation < ActiveRecord::Base
+  validates :title, :content, presence: true
+  validates :title, uniqueness: true
+
+  self.per_page = 50
+
+  def original_url
+    "https://projecteuler.net/problem=#{id}"
+  end
+end