Can somebody link some videos (or other stuff) for studying expressions and equations like the math with the letters? I'm struggling and I defiantly need to study but I can't find anything. :)

One video you can watch is https://www.khanacademy.org/math/cc-sixth-grade-math/cc-6th-equations-and-inequalities/cc-6th-intro-equations/v/variables-expressions-and-equations

since the airplane is moving with constant speed then the distance travelled can be calculated by x=u*t

in km/h would be:

x=640*3.5=2.240 km

in m/s would be:

u=640 km/h= 640.000 m/h =640.000/ 3600 m/s =177.8 m/s

t= 3.5 h= 3.5 * 3600 s=12.600 s

then x=u*t= 177.8*12.600= 2.240.280 m

8496 cars

step-by-step explanation: