Question 1151481
The equation {{{d=3t+15}}} 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+b}}}

use two points from given table to find slope {{{m}}}:

{{{m=(30-20)/(10-5)}}}
{{{m=10/5}}}
{{{m=2}}}

{{{y=2x+b}}}.....use one point to find {{{b}}}

{{{40=2*15+b}}}
{{{40=30+b}}}
{{{40-30=b}}}
{{{b=10}}}
{{{y=2x+10}}}

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