Question

In four years' time, Kim's father will be three times as old as Kim. Six years ago, her father was seven times as old as her. By letting x and y be Kim's present age and Kim's father's age respectively, form two equations to find Kim's present age.

Answer 1

Answer:

Let x and y be the present age of father and his son.

According to the question,

x−5=7(y−5)

x=7y−30.....(1)

Also,

x+5=3(y+5)

x+5=3y+15

7y−30+5=3y+15(From (1))

7y−3y=15+25

⇒y=

4

40

=10

Substituting the value of y in equation (1), we have

x=7×10−30=70−30=40

Hence the present age of father and his son is 40 and 10 years respectively.

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