Two planes left the same airport traveling in opposite directions. the first plane left at 9: 00 a. m. and 2.25 hours later, the two planes were 1825 miles apart. the second plane left at 10: 00 a. m. and its average rate was 108 miles per hour slower than the first plane's average rate. let x represent the first plane's average rate. what was the first plane's average rate? enter an equation that can be used to solve this problem in the first box. solve for x and enter the first plane's average rate in the second box.