Well, it might be a bit tricky, but it's below.

Question

Breaker's Manufacturing Company makes 80% of a particular sensor, the Cartin Company makes 15% of them, and the Flutes Company makes the other 5%. The sensors made by Breaker's have a 4% defect rate, the Cartin sensors have a 6% defect rate, and the Flutes sensors have a 9% defect rate. If a sensor is randomly selected from the general population of all sensors, what is the probability that it is defective, given that it was made by Breaker’s?

Answer 1

Actually, this one's really easy....but there's a lot of extraneous information. The "given" is a key that you're computing a conditional probability, specifically:

Prob(Defective | Made By Breaker's)

and this is simply the defective rate for Breaker's, which was given as 4%.

Answer 2

I think there may be a typo in the last question. I've given answers for three possible interpretations.