Thomas always saves 20% of his monthly salary. His salary for December was 25% more than that for November. His savings for December increased by $127 as a result. What was his salary for November?
n =nov salary
d = december salary = 1.25 n
0.2 d - 0.2 n = 127
d - n = 635
1.25 n - n = 635
0.25 n = 635
n = 2540