First large city-state of the americas

for this case we have the following equation:

we apply distributive property to the terms within parentheses.

subtracting 2 on both sides of the equation:

answer: the time zones used to be whatever the local authority wanted them to be. one town might have 6am whenever the sun came up and another town had 6am 10 minutes later.  

the trains had a hard time when their orders said to be at a certain point at 6am.  

6am, but who's 6am.  

the railroads got together and set the time zones more or less along the longitude lines across the country.

explanation: