You're both right

.
Certain exercises do strenghten certain muscle groups - ab exercises target ab muscles, arm exercises target biceps and triceps muscles, etc. So Misti's right when she says that it's possible to work on certain areas of our body with specific exercises. Yes, you absolutely can build and strengthen targeted muscles with specific exercises.
But Kylie's right that you can't spot reduce
fat. You gotta keep in mind that there's a difference between
fat and
muscle. Exercise will strengthen the muscle that lies underneath the fat - but it can't make the fat layer on top go away. That happens with cardio and diet. You can do a thousand crunches a day and have a six-pack -- but if you've got a couple inches of fat on top, no one will ever be able to see it.
Everyone's got one or two problem spots that hold the fat and they're usually the LAST to go - but they will go eventually! Your body is going to use up its stored fat in whatever order it wants to (usually the last on is the first off) and the key is patience and sticking to your eating and exercise plans.
