Please help me solve this quickly!

How to find the exponential function y=ca^x, with points (1,2) and (2,1)

Atrain leaves little? rock, arkansas, and travels north at 90 kilometers per hour. another train leaves at the same time and travels south at 80 kilometers per hour. how long will it take before they are 680 kilometers? apart?

The pair of coordinates that do not represent the point( 5,150’) is a. (5,-210) b. (5,210) c. (-5,330) d. (-5,-30)