There is an unstated assumption here, you are supposed to assume that the state of the patients blood pressure and cholesterol level are independent. This is the assumption you are expected to make because the question provides no additional information to allow you to do anything else.

Assume there are 10000 patients then 1300 have high cholesterol, and of these 0.17*1300~=221 also have high blood pressure.

So the probability that they has high blood given that they have high cholesterol is 221/1300 = 0.17.

RonL