Question

a truck cover a distance of 510 km in 34 listers of diesel.how much distance would it cover in 20 litres of diesel.

Answer 1

Total dis. Cover = 510 km
total diesel =34 liter
1 liter diesel cover = 510/34 =15 km
in 20 liter diesel =15*20= 300 km
Thank,s 

Answer 2

let the distance be x.
then
distance covered - 510 km x
quantity of diesel - 34. 20
since if the quantity of diesel decreases then distance covered also decreases
hence they are directly proportional.
then,
510/34=x/20
then,
$34x = 510 \times 20$
$x = 510 \times 20 \div 34$
so,
required distance =300 km