1000m equals 1km so 600m equals 0.6km.
15x-10=20
+10 +10
15x=30
\15 /15
x=2
you add 10 to both -10 (they cancek eachother out) and 20 (equals 30)
Then you divide 30 by 15 (equals 2) and 15 by 15 (they cancel eachother out)
Then you get x=2
The answer is B. It’s not too difficult