What are the two main types of land pollution?

Two cyclists 84 miles apart start riding toward each other at the samen time. one cycles 2 times as fast as the other. if they meet 4 hours later what is the speed (in miles) of the faster cyclists

Which spreadsheet would be used to compute the first nine terms of the geometric sequence a^n=32•(1/2)n-1

Could someone me with this question i’ve been stuck on it for 20 minutes