Question 8822
The equation that describes the distance that car has travelled for specific period of time is: U(t)=S(t)/t,    U(t):speed(km/h) |
                                   S(t):distance(km)| we firstly convert min  
                                      t: time(min)  |  to hr
In our problem, S(t1)=U(t1)*t1
              =>S(t1)=40*0,5=20km
                S(t2)=U(t2)*t2
              =>S(t2)=60*(1/4)=15km
So the final distance travelled is S=S(t1)+S(t2)=20+15=35km