A bicycle wheel whose radius is 30 cm covered a distancein 70 revolutions.how many kilometres was this distance

One rotation = 2π(30) cm = 60π cm

so 70 rotations = 70(60π) = 4200π cm
= appr 13194.7 cm
= 131.947 m
= .131947 km

how about appr .13 km ? , you don't specify what accuracy.