Congruent polygons and how to find the measure of numbered angles

The circumference of a redwood tree trunk is 20π ft, and it is 100 ft tall. what is the approximate volume of the redwood tree trunk? 1,000π ft3 10,000π ft3 4,000π ft3 40,000π ft3

∆red ≅ ∆ by rule will give brainiest if possible

Using elimination, what is -4x+2y=-12 4x+8y=-24