# Sarin’s father crossing the Causeway part 8 (Math Question)

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Read posting on Sarin’s father visits his friend in JB town to know about JB town as well as reading posting on Sarin’s father crossing the Causeway to know about the Johor-Singapore Causeway.

Read also posting on Sarin learns rate of change in school (Math Concept) to learn about concept of speed and relative speed.

Upper primary school mathematics question UPQ146

The distance between JB Central and Simei was 520 km. At 8.30 a.m., a van left JB Central for  Simei travelling at a constant speed. At the same time, Sarin’s father drove a car travelling at a constant speed set off from Simei towards JB Central. The two vehicles met each other at 12.30 p.m. The car was travelling at 20 km/h faster than the van. What was the speed of the car that drive by Sarin’s father?

Solution:

The van and the car start at 8.30 a.m and met at 12.30 p.m

Time required to travel the distance = 4 hours

The relative speed between the car and van = 520 ÷ 4 = 130km/h

As both travelled in opposite direction, we can have the below model based on speed

2U + 20 = 130

1U = 110 ÷ 2 = 55km/h

The speed of the car = 55 + 20 = 75km/h