Answer
2.4 texts
Work Step by Step
increase = nbr in 2011 - nbr in 2010
$d=41.5-39.1=2.4$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.