2000 x 5/100 = 100 (this is 5% of 2000) after 1 year the number of students increases by 100 yeilding 2100 students.
2100 x 5/100 = 105 (5% of 2100) after 2 years the number of students increased by 105, overall there were 205 more students over the 2 year period.
2000+205= 2205 students after 2 years.