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
It is important because if you are adding and subtracfing and the decimals are off when your done with the equation you might end up with two decimals or numbers in the wrong place