8錯。恭喜。

let xn = the current salary,
x3 = the salary 3 years ago
x2 = the salary 2 years ago
x1 = the salary 1 year ago

thus, xn = 2.4 x3
xn = 1.7 x2
xn = 1.14 x1

Assume, the current salary xn =240000
the x3 = 100000
x2 = 141176.47
x1 = 210526.32

Based on the common sense, the average salary of IT was more than 100000 3 years ago.

It can be conjectured that LZ's current salary > 250000 :)

Not bad:)