The first number refers to systolic pressure, and the second number refers to diastolic pressure.
Blood pressure varies from person to person, as well as from time to time in the same person.
It is influenced by general health, heredity, age, activity, and emotional state. Normal systolic blood pressure for adults is about 120 mmHg. Pressures constantly over 150 mmHg are consider high. Doctors also consider diastolic pressures over 90 mmHg to be high. However, blood pressure usually rises with age because the arteries become less elastic and slow down the flow of blood.