In a certain town, 25 % of the families own a phone and 15 % own a...

Let set $A$ contains families which own a phone and set $B$ contain families which own a car.

If $65$ families own neither a phone nor a car, then $35$ will own either a phone or a car

$∴ n\left(A \cup B\right) = 35$

Also we know that

$n\left(A \cup B\right) = n\left(A\right) + n\left(B\right) - n ( A \cap B )$

$35 = 25 + 15 - n ( A \cap B )$

$n\left(A \cap B\right) = 5$

$5$ families own both phone and car and it is given to be $2000$ .
$∴ 5$

$\dfrac{5x}{100} = 2000$

$x = 40000$

Hence, \left(i\right), $\left(ii\right) and \left(iii\right)$ are correct.