Problema Solution
Robert's thinking about that his father is 7 years more than twice his own age, and his grandfather is 4 years less than twice his father's age. if Robert's grandfather is 70 years of age, how old is Robert?
Answer provided by our tutors
let
x = the age of Robert
y = the age of his father
his father is 7 years more than twice his own age:
y = 2x + 7
his grandfather is 4 years less than twice his father's age and his grandfather is 70 tears of age:
70 = 2y - 4
2y - 4 = 70
plug y = 2x + 7 into the last equation:
2(2x + 7) - 4 = 40
by solving we find:
x = 7.5 years
click here to see the step by step solution of the equation:
Robert is 7 and a half years old.