Q1. Kelly and Tom started walking from the same starting point but in the opposite directions along a straight path. Kelly's average speed was 4km/h faster than Tom's. After walking fo 3 hours, they were 40km apart. What was Kelly's average speed?

**Solution**:

If Kelly's speed is 4 km/h faster than Tom's,

then after 3 hours, she would have travelled 4 km/h x 3 h = 12 km more than Tom

If they are 40 km apart, then sum of distances travelled by both = 40 km (because they went in opposite directions)

Therefore, Kelly's distance is (40 + 12)/2 km = 26 km

And, so her average speed = 26 km/3 h = **8 2/3 km/h**

check:

Tom's distance = (40 - 26) km = 14 km

and his speed = 14 km/3 h = 4 2/3 km/h, which is 4 km/h slower than Kelly's