If the mean of the data given in adjoining table is 20, the relation between x₁ and x₂ is :

x	f	fx
10	x1
20	20
30	x2

1. x₁ + x₂ = 30

2. x₁ - x₂ = 15

3. x₁ - x₂ = 0

4. x₁ + x₂ = 20

By formula,

Mean = $\dfrac{Σfx}{Σf}$

Substituting values we get :

$\Rightarrow 20 = \dfrac{400 + 10x$1 + 30x2}{20 + x1 + x2} \\[1em] \Rightarrow 20(20 + x1 + x2) = 400 + 10x1 + 30x2 \\[1em] \Rightarrow 400 + 20x1 + 20x2 = 400 + 10x1 + 30x2 \\[1em] \Rightarrow 20x1 - 10x1 + 20x2 - 30x2 = 400 - 400 \\[1em] \Rightarrow 10x1 - 10x2 = 0 \\[1em] \Rightarrow 10(x1 - x2) = 0 \\[1em] \Rightarrow x1 - x2 = 0.

Hence, Option 3 is the correct option.