SOLUTION: Mrs. De Guzman is 28 years old when her daughter was born. In how many years will Mrs. De Guzman be thrice as old as her daughter.

Let x be "in how many years . . . ".


Then you have this equation


    x + 28 = 3x.


The left side is the mother's age in 28 years; the right side is her age then, expressed via the daughter's age.


From the equation


    28 = 3x - x

    28 = 2x

    x  = 28/2 = 14.


ANSWER.  In 14 years.


CHECK.  In 14 years, the mother will be 28 + 14 = 42 years old;

                     the daughter will be         14 years old.   ! Ok, good, i.e. CORRECT !