question: Louise is an artist and needs to apply a coat of varnish to her latest paintings. Usually it takes 7 minutes for the coat of varnish to dry on one painting. However, today she is using a new varnish and it takes 12 minutes for the coat to dry. How much longer will it take for the coat of varnish on 6 paintings with the new varnish to dry as it would with the old varnish?
answer: Usually, the varnish on all 6 paintings would be dry in 7*6=<<7*6=42>>42 minutes
  With the new varnish, all 6 paintings would be dry in 12*6=<<6*12=72>>72 minutes
  With the new varnish, it will take 72-42=<<72-42=30>>30 more minutes
  #### 30