If y varies directly to x and y = 80 when x = 400; the value of y when x = 25 is:

1. 5

2. 25

3. 75

4. 125

Let the value of y when x = 25 be a

Since it is a case of direct variation,

$\therefore \dfrac{400}{80} = \dfrac{25}{a}\\[1em] \Rightarrow a = \dfrac{80 \times 25}{400}\\[1em] \Rightarrow a = \dfrac{2,000}{400}\\[1em] \Rightarrow a = 5$

Hence, option 1 is the correct option.