In an organisation, an employee retires when the sum of his/her age and the number of years he/she has worked in the organisation is 77. At present, Mahesh is 37 years old and Suresh is 41 years old. Also the sum of the number of years for which they have worked in the organisation is 20. If Suresh will retire five years after Mahesh, then for how many years would Suresh have worked in the organisation at the time Mahesh retires?