In week 5 the Lions hosted the St. Louis Rams. The Lions started the scoring early with a 30-yard Jason Hanson field goal. The Rams tied it up at the end of the first quarter with a 28-yard field goal by Josh Brown. To start the second quarter, the Lions took the lead with a 105-yard kickoff return by Stefan Logan, the longest touchdown run in the NFL this season. The Lions added to their lead a few minutes later with a 1-yard TD catch by Calvin Johnson. The Rams kicked another 28-yard field goal a few minutes later. The Lions made it 24-6 just before halftime with a 3-yard TD catch by Brandon Pettigrew. The Lions' defense shut out the Rams in the second half. The only score of the third quarter was a 26-yard TD catch by Nate Burleson. In the fourth quarter the Lions kicked 2 field goals: from 48 then from 47. The Lions capped off their victory with a 42-yard interception return TD by Alphonso Smith.  With the win, not only did the Lions improve to 1-4, but it was their largest margin of victory since 1995 and their first win since November 22, 2009.
Question: How many points were the Rams trailing by at halftime?
Answer: 18