Question 1151481
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The question is about the distances from the wall that Jon's and Brianna's cars are at the beginning (at t=0).<br>
The distance Jon's car is at the beginning can be found by evaluating the given equation at t=0: 3(0)+15 = 15.  His car starts 15 feet from the wall.<br>
To find the distance Brianna's car is from the wall at the beginning, you could use formal mathematics as the other tutor did to find an equation for the distance from the wall of her car, and then evaluate that equation at t=0.<br>
But the beginning distance of Brianna's car from the wall can be found informally very quickly, by observing that the given data shows her car moves 10 feet every 5 seconds.  Since it was 20 feet from the wall after 5 seconds, it was 10 feet from the wall at the beginning.<br>
And so Brianna's car started 5 feet closer to the wall than Jon's.<br>