Answer:
Explanation:
Roberts's father=4x
Robert=x
After 5 years, the ages will be
4x+5 and x+5 because we just simply add 5 years to their ages
It says that the father will be 3x older. So,
3(x+5)=4x+5. --this is the equation
3x+15=4x+5
-5 -5
3x+10=4x
-3x -3x
x=10