It is given that Roberts father is 5 years older than 3 times Robert's age which means that Roberts Father's age is 5 years more than 3 times the age of Roberts
∴ Roberts Father's age is: 3 times of Robert age + 5 years
Try this solution: 1. if 1st number is 'x', the 2d number is 'y', then it is possible to make up the system of two equation according to the condition: 2. one number is 11, another number is 10.