SOLUTION: Jon's and Brianna were racing remote control car. The equation d=3t+15 models the distance, d( in feet), Jon's car was away from a wall, after t seconds. The second. The table belo

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Question 1151481: Jon's and Brianna were racing remote control car. The equation d=3t+15 models the distance, d( in feet), Jon's car was away from a wall, after t seconds. The second. The table below shows the distance that Brianna's car was away from the same wall at different times.
Seconds(t) Feet from wall (d)
5. 20
10. 30
15. 40
How much closer to the wall did Brianna's car start compared to Jon's car?
A. 1ft
B. 2ft
C. 5ft
D. 10 ft
Found 2 solutions by MathLover1, greenestamps:
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
The equation d=3t%2B15 models the distance, d( in feet), Jon's car was away from a wall, after t seconds.
Seconds (t) Feet from Wall (d)
+5 ................ 20
10............ 30
15 ............. 40
first find the equation which models the distance, d( in feet), Brianna’s car was away from a wall, after t seconds
y=mx%2Bb
use two points from given table to find slope m:
m=%2830-20%29%2F%2810-5%29
m=10%2F5
m=2
y=2x%2Bb.....use one point to find b
40=2%2A15%2Bb
40=30%2Bb
40-30=b
b=10
y=2x%2B10
as you can see, y-intercept in equation for Jon's car is 15 and y-intercept in equation for Brianna’s car is 10 , the difference is 5
and that is how much closer to the wall did Brianna’s car start compared to Jon’s car

C. 5 ft=>your answer

Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


The question is about the distances from the wall that Jon's and Brianna's cars are at the beginning (at t=0).

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.

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.

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.

And so Brianna's car started 5 feet closer to the wall than Jon's.