Problem 3. Martin is 3 times younger than his father, and together they are 44 years old. In how many years will Martin be 2 times younger than his father.
Solution. First method. Let the age of Martin be denoted by $x$, and the age of his father by $y$. From the condition, we have $x+y=44, y=3x$, from which it follows that $x+3x=44$, i.e., $4x=44$, so $x=11$. From this, $y=33$. Let the number of years after which Martin will be half the age of his father be $z$. Then $2(11+z)=33+z$, i.e., $22+2z=33+z$, from which $z=11$. Therefore, at the moment, Martin is 11 years old, and his father is 33 years old, and after 11 years, Martin will be half the age of his father, i.e., he will be 22 years old, and his father will be 44.

Second method. Let the age of Martin be denoted by $x$. Then his father will be $3x$ years old. Together, they will be $4x$ years old, i.e., $4x=44$, so $x=11$. Therefore, Martin is 11 years old, and his father is 33 years old.

Let the number of years after which Martin will be half the age of his father be $z$. Then $22+2z=33+z$, from which we have $z=11$. Therefore, after 11 years, Martin will be half the age of his father, i.e., he will be 22 years old, and his father will be 44.