Distance travelled on foot = 1 km 70 m = 1.070 km (we know that 1 km = 1000 m)
Suppose distance travelled by bus = x km
Total distance of school from residence = 5 km 350 m = 5.350 km
So, 1.070 + x = 5.350
x= 5.350 - 1.070
x= 4.280 km
Therefore, distance travelled by bus = 4.280 km