Hey how are u guys doing

Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

What can you learn about precipitation levels in south america from this map? brazil is experiencing a drought.it rains more in higher altitudes.peru received the highest level of rain.venezuela got less than 25 cm of rain. 

Chris lives in a city that experiences heavy rainfall with average annual precipitation of 882 millimeters. it is warm all year.mark lives in city with an average annual rainfall of 40 millimeters. it has hot summers and cool winters.chris's city is in a climate, while mark's city is in a climate.