Mensah is 5 years old and joyce is thrice as old as mensah. In how many years will joyce be twice as old as Mensah?

  • A 3 years
  • B 10 years
  • C 5 years
  • D 15 years
waec 2021mathematics

The correct answer is C. 5 years

Mensah’s age is 5. Thus,

Joyce’s age is 15 (5*3=15)

The difference between their ages is 10 (15–5=10)

As we ought to find how many years Joyce’s age will be twice of Mensah’s age, we should write down the following :

15+X=2*(5+X)

15+X=10+2X lets add (-10-X) to both sides of the equation and

15+X-10-X = 10+2X-10-X

5=X —-> X=5

After 5 years Joyce’s age will be 20 (15+5=20)

After 5 years Mensah’s age will be 10 (5+5=10)

After 5 years Joyce will be twice as old as Mensah (10*2=20)

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