Weekly domestic violence arrests in an urban area of St. Louis increased from 102 in 2006 to 123 in 2009.

In (2009-2006)=3 yrs number of weekly domestic violence arrests increased by (123-102)=21 at the rate of 21/3=7 per yr.

Therefore, in 2013, i.e., after 4 yrs of 2009, number of weekly domestic violence arrests will be (123+7 x 4)=151.