We will use the distance formulas, however the problem warns us that the car starts from rest, this is important because we know that the initial speed will be zero, that is:
[tex]\boldsymbol{v_{o}=0 }[/tex]
Now the data we have is:
We will apply the following formula:
[tex]\bf{d=\dfrac{at^2}{2 } }[/tex]
Substituting our data:
[tex]\bf{d=\dfrac{at^2}{2 }=\dfrac{(3.5)(7)^2 }{2}=\dfrac{171.5}{2}=85.75 \ m }[/tex]
So our car will have traveled 85.75 meters after 7 seconds.