Property Income

Janet granted a lease to Jack on 1 March 2014 for a period of 40 years. Jack paid a premium of 25000.
But regranted a lease to Jill on 25 March 2014 for a period of 10 years. Jill paid a premium of 15000.

Is it right to calculate the Jack’s property incom like this?

Premium………………………………………15000
(-) 15000 x (10-1) x 2%…………………….(2700)
`
………………………………………………….12300
(-) 5500 x 10/40………………………………(1375) W

Property Income ……………………………..10925

Working
Premium…………………………………..25000
(-) 25000 x (40-1) x 2%………………..(19500)
`
………………………………………………5500