i just did this question... hahah
first you have to know that time=distance/speed
so the distance is 1000 and the speed is v
therefore, time=1000/v
once you have that we have to calculate the wages and the cost per litre separately
so for the wages you times 1000/v by 60
= 60000/v
now for the cost per litre you have to times it by the time and by the rate of fuel
so multiplying 1000/v by 1.50 and then (6+v^2/50)
= 1.50 x 1000/v x (6+v^2/50)
when you expand the brackets you get 9000/v +30v
Total Cost = 6000/v + 9000/v + 30v
C = 69000/v + 30v
the main thing you have to figure out is the distance/speed part and once you have that everything should fall into place