Jasmin's dog weighs 58 pounds. Her vet told her that a healthy weight for her dog would be less than or equal to 40 pounds. Jasmin's dog can lose an average of 1.5 pounds every week. Write the solution to an inequality that describes all possible number of weeks for which her dog can be at a healthy weight.

Let $w$ represent the number of weeks that Jasmin's dog needs to lose weight.

The initial weight of Jasmin's dog is 58 pounds and the healthy weight is 40 pounds. To lose weight, the dog needs to lose
$58-40=18$ pounds.

Given that the dog can lose 1.5 pounds every week, we can write the inequality:

$1.5w \geq 18$

Dividing both sides by 1.5:

$w \geq 12$

Therefore, all possible number of weeks for which her dog can be at a healthy weight is:

$\boxed{w \geq 12}$