You can 
put this solution on YOUR website! .
A family plans to drive 856 km to their holiday home.
a)  At what speed should they travel on average if they want to get there in 10 hours?
    - To answer this question, divide miles by hours.
b)  they left at 6am and arrived at 8pm.  How long did the trip take?
    - Look on the face of the watch and answer on your own.
      Six hours before noon and 8 hours after.
c)  Calculate their average speed( 1 decimal place)
      - I assume you completed n.b).
        Then divide miles by your time value from the question b).  Do it on your own.
d)  How far could they have travelled at the speed in question c if they only drove for the original 10 hours planned? ( answer to nearest km)
    - To answer this question, multiply the speed of the question c)  by 10 hours.
They are SO SIMPLE questions . . . THERE IS NO MORE SIMPLE in the school . . . 
You can do it on your own.       <---   --->     EVERYBODY can do it !
If you can do it     <---   --->     (EVERYBODY can do it !),     <---   --->     do not post such simple problems to the forum.
Do as much on your own as you can.
                    H a p p y   l e a r n i n g  ! !