We will highlight the downheap bubbling which took place at each stage.

Here is the original heap:

After first call to removeMin() (which removes '3'):

After second call to removeMin() (which removes '6'):

After third call to removeMin() (which removes '8'):

After fourth call to removeMin() (which removes '9'):

After fifth call to removeMin() (which removes'11'):

Here is a brief explanation. Recursively traverse the tree but only so long as you are at a node which is less than or equal to the given x. If you reach a node which is greater than x, there is no need to traverse deeper in that subtree because all other keys are known to be at least as big as the key at such a node. The overall number of nodes visited will be at most (1+2k), where k is the number of keys actually less than or equal to x.