What is relative speed between two objects ?

Hint:“In relation to” is what “relative” means. When we claim that an object has a certain velocity, we're referring to the velocity in relation to a reference frame. When we calculate the velocity of an object in daily life, we use the ground or the earth as our reference point. This phenomenon is known as relative motion.

Complete step by step answer:
Relative speed refers to the speed of a moving body in comparison to another. The difference between two bodies travelling in the same direction is used to measure their relative speed. However, when two bodies are moving in opposite directions, the relative speed is calculated by combining their speeds.

The difference between relative velocity and relative speed is that relative velocity is a vector value, whereas relative speed is a scalar value.Calculation of relative speed when two objects move in the same direction –
Assuming the speed of first object - $x\,km/h$
Assuming the speed of second object - $y\,km/h$
So, the relative speed will be $(x - y)$ $if$ $(x > y)$
When two object meets, time = $\dfrac{\text{distance}}{\text{relative speed}}$ = $\dfrac{d}{{x - y}}$

Since, the speed of one object with respect to other is known as relative speed and if the time $t\,hrs$ is given when they meet then,
The distance covered in $t\,hrs$ is given as = time x relative speed = $t \times (x - y)$
Calculation of relative speed when two objects move in the opposite direction –
Assuming the speed of first object - $x\,km/h$
Assuming the speed of second object - $y\,km/h$
So, the relative speed will be $(x + y)$ $if$ $(x > y)$
When two object meets, time = $\dfrac{\text{distance}}{\text{relative speed}}$ = $\dfrac{d}{{x + y}}$
Since, the speed of one object with respect to other is known as relative speed and if the time $t\,hrs$ is given when they meet then,
The distance covered in $t\,hrs$ is given as = time $x$ relative speed = $t \times (x + y)$

Note:The relative speed of two bodies travelling in opposite directions is equal to the number of their individual speeds. The relative speed is equal to the difference between their individual speeds if they are going in the same direction.