Last month the mail carrier delivered mail on the morning route 16 times and on the afternoon route 12 times for a total distance of 141 miles. This month the mail carrier delivered mail on the morning route 10 times and on the afternoon route 15 times, for a total distance traveled of 123.75 miles. What is the distance of the morning route in miles?

Let x be the distance of the morning route in miles.

From the information given:

16x + 12(141 - x) = 141
16x + 1692 - 12x = 141
4x = 1692 - 141
4x = 1551
x = 1551 / 4
x = 387.75 miles

Therefore, the distance of the morning route is 387.75 miles.