Help me please I don't know what to do

Of the ones listed here, the factor that had the greatest impact on the eventual destruction of native americans' ways of life was the development of the a) automobile. b) highway. c) railroad. d) steamboat.

How much higher is checkpoint 4 than checkpoint 2 if checkpoint 4 is -143 and checkpoint 2 is -182

Given a circle with measures of (c, d, and r) and a circle with measures of (c', d', and r'), find r' if c c' = 0.25 and d = 6.0. a. 6 b. 12 c. 18 d. 24