X, Y and Z invested for certain time and the ratio of profit was 10 ∶ 15 ∶ 12. The amount Y invested was 15000 more than the amount invested by X, who invested 20,000 less than the amount invested by Z. X and Y invested for 5 and 3 years respectively. Find the time duration for which Z invested.
1
5 years
2
4 years
3
3 years
4
2 years