Today Katherine, who is 40 years old, and her daughter, who is 10 years old, celebrate their birthdays. How many years will pass before Katherine’s age is twice her daughter’s age?  Choose one:  A) 22  B) 20  C) 23  D) 24  E) 25
Forget conventional ways of solving math questions. In PS, IVY approach is the easiest and quickest way to find the answer.   After x years passes Katherine’s age will be (40+x) years old, and her daughter’s age will be (10+x) years old. Since the Katherine’s age is twice her daughter’s age (40+x)= 2 * (10+x) ---&gt; 40+x=20+2x ---&gt; x= 20.   The answer is (20).
<result>B</result>
Today Katherine, who is 40 years old, and her daughter, who is 10 years old, celebrate their birthdays. How many years will pass before Katherine’s age is twice her daughter’s age?