Five years ago, A's age was four times the age of B. Five years hence, A's age will be twice the age of B. Find their present ages.
Linear Equations
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Question

Five years ago, A's age was four times the age of B. Five years hence, A's age will be twice the age of B. Find their present ages.

KnowledgeBoat · Accepted Answer

Let present age of A be x years and B be y years. Five years's ago their age will be : A = (x - 5) years B = (y - 5) years Given, Five years ago, A's age was four times the age of B. ⇒ (x - 5) = 4(y - 5) ⇒ x - 5 = 4y - 20 ⇒ x = 4y - 20 + 5 ⇒ x = 4y - 15 .........(1) Five years's later their age will be : A = (x + 5) years B = (y + 5) years Given, Five years hence, A's age will be twice the age of B. ⇒ (x + 5) = 2(y + 5) ⇒ x + 5 = 2y + 10 ⇒ x = 2y + 10 - 5 ⇒ x = 2y + 5 .........(2) From (1) and (2), we get : ⇒ 4y - 15 = 2y + 5 ⇒ 4y - 2y = 5 + 15 ⇒ 2y = 20 ⇒ y = = 10 years. Substituting value of y in equation (2), we get : ⇒ x = 2(10) + 5 = 20 + 5 = 25 years. Hence, present age of A = 25 years and B = 10 years.

Mathematics

Five years ago, A's age was four times the age of B. Five years hence, A's age will be twice the age of B. Find their present ages.

Linear Equations

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