Method of Substitution to Find the Solution of a Pair of Linear Equations
Four years ag...
Question
Four years ago, a mother was four times as old as her daughter. Six years later, the mother will be two and a half times as old as her daughter at that time. Find the present ages of mother and her daughter.
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Solution
let daughter's age=x 4 yrs ago age=(x-4) mother's age=4(x-4) =4x-16 present age of mother= 4x-16+4 =4x-12 6 yrs later daughter's age=x+6 mother's age=4x-12+6 = 4x-6 atq = mother's age= 5x/2 + 15 4x-6 = 5x/2 +15 8x-5x /2 =21 x= 21*2/3 x=14 mother's age = 44 yrs daughter's age =14 yrs