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?
Usually, the varnish on all 6 paintings would be dry in 7*6=
<gadget id="calculator">7*6</gadget>
<output>42</output>
42 minutes.
With the new varnish, all 6 paintings would be dry in 12*6=
<gadget id="calculator">6*12</gadget>
<output>72</output>
72 minutes.
With the new varnish, it will take 72-42=
<gadget id="calculator">72-42</gadget>
<output>30</output>
30 more minutes.

<result>30</result>