lan completed part of a race and had 2000m

Question

left to run.if he had completed 3/5 of the race,what is the total distance he had to run?

Let the total distance be x m
since he completed 3/5 of the race, he still has 2/5 of the race to run, but this is supposed to be 2000 m

then (2/5)x = 2000
multiply both sides by 5/2,

(5/2)*(3/5)x= 5/2*2000
x=5000 m

typo in second-last line

should be: (5/2)*(2/5)x = 5/2*2000