How many calories should a 42 year old woman who is 5'5 and weighs 156 pounds eat to lose 2 pounds a week?

Well, for starters, 5'5" and 156 pounds is pretty good. As the expression goes, "if I wanted a woman with the shape of a 10-year-old boy, I'd just date a 10-year-old boy."

Now, to answer your question:

To permanently lose weight, you must drop 3600 calories from your diet for each pound. To lose 2 pounds, you'd have to eat 7200 fewer calories per week. While 100 calories a day seems like a small amount (one less donut / coffee every day) it's harder than it looks.

If you do that, you're going to put your body into "starvation mode". You'll lose muscle, not fat, and you're almost guaranteed to binge and get into a guilt mode. Ease into it and exercise more. Bike to work, jump rope, and do push-ups / sit-ups before bed.

Don't skip breakfast.