Question 625270

Johen is hulf his father's age now. Fifteen years ago,he was one-third of his father's age. How old wil johe be after 5 year?


Let Johen's age be J, and his father's, F


Then: {{{J = (1/2)F}}} ------ F = 2J ---- eq (i)


Also, {{{J - 15 = (1/3)(F - 15)}}} ----- {{{J - 15 = (F - 15)/3}}}


3J - 45 = F - 15 ----- Multiplying by LCD, 3


3J - F = 30 ----- eq (ii)


3J - 2J = 30 ------ Substituting 2J for F in eq (ii)


J, or Johen is currently 30 years-old


In 5 years' time, Johen will be {{{highlight_green(35)}}} (30 + 5)


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Check
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Johen's current age: 30


Johen's age 15 years ago: 15 (30 - 15)


Father's current age: 60


Father's age 15 years ago: 45 (60 - 15)


15 years ago, Johen's age (15) was {{{1/3}}} his father's age then (45)


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