define method for job count

app/models/city.rb

@@ -19,4 +19,8 @@ class City < ApplicationRecord
 
   scope :vn_cities, -> {where region: "Việt Nam"}
   scope :inter_cities, -> {where region: "#"}
+
+  def job_count
+    jobs.count
+  end
 end

app/views/cities/_city.html.erb

 <div class="col-md-3">
   <div class="col-show">
-    <%= city.name %> (<%= (city.jobs.count) %>)
+    <%= city.name %> (<%= (city.job_count) %>)
   </div>
 </div>