X=v*t problem?

Question

A truck is going from A to B.
the speed of the truck is 70km/hour
A cab is going from B to A.
the speed of the cab is 90 km/hour.
when will the two meet?
please show the way

the distance between A and B is 80 km.

Answer 1

As you added, A to B is 80 km

let's call the distance D
so the total displacement of the two vehicles is D
for the truck
xt(t)=70*t where t is in hours and x is in km

for the cab
xc(t)=90*t
when the two meet xt+xc=D and they have a common t
so add them together
xt+xc=D
D=70*t+90*t
t is the time they meet
t=D/160 hours
since D=80km, then
t= 30 minutes

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