Employees at Grindstone Ltd are paid a weekly wage according to the following formula: £240 + £5 for every year of their age above 21 (where appropriate) + £20 for every full year of service with the company. Jasper is 43 years old and has worked for Grindstone for 6 years. Although Ruby is 8 years younger, she earns £40 per week more than Jasper.