Answer:
Their present ages are:
Robert is 10 years old and his father is 40 years old.
Step-by-step explanation:
Let be "r" Robert's present age and "f" his father's present age.
Based on the information given in the exercise, you can set up the following system of equations:
[tex]\left \{ {{f=4r} \atop {f+5=3(r+5)}} \right.[/tex]
Use the Substitution Method and substitute the first equation into the second one and then solve for "r":
[tex]4r+5=3(r+5)}\\\\4r+5=3r+15\\\\4r-3r=15-5\\\\r=10[/tex]
Substitute the value of "r" into the first equation and evaluate:
[tex]f=4(10)\\\\f=40[/tex]
