Describe the domain for d=f(c)

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.

Aswimming pool had 2.5 million liters of water in it. some water evaporated, and then the pool only had 22 million liters of water in it. what percent of the water evaporated?

Simplify. 4+3/7x-2-2/7x a. 2-5/7x b. 6-1/7x c. 2+1/7x d. 6+5/7x