Question

right now Christina is twice as old as mark. in five years, she will be 50% older than him. how many years old is Christina now?

Answer 1

Answer: Age of Christina is 10 years.

Explanation:

Let the age of Mark be x.

Let the age of Christina be 2x.

After 5 years,

Age of Mark would be x + 5

Age of Christina would be 2x + 5.

According to question, our equation becomes

2x+5 = 1.5(x+5)

2x+5= 1.5x + 7.5

2x-1.5x = 7.5 -5

0.5 x= 2.5

x = 2.5 ÷ 0.5

x = 5 years

Hence, age of Christina would be 2x = 2×5 = 10 years

Answer 2

Christina is 10 years old now

Explanation:

- Right now Christina is twice as old as mark

- Assume that mark now is x years old

∵ Mark is x years old

∵ Christina is twice as old as mark

∴ Christina is 2 x years old

- In five years, she will be 50% older than him

∵ Mark is x years old now

∴ In five years mark will be x + 5 years old

∵ Christina is 2 x years old now

∴ In five years Christina will be 2 x + 5 → (1)

∵ In five years Christina will be 50% older than him

- Assume that he will be 100% year and she is older by 50%, then she

will be 150% ⇒ (100% + 50%)

∵ 150% =
`(150)/(100)=1.5`

∴ In five years Christina will be 1.5(x + 5) → (2)

- Equate (1) and (2)

∴ 2 x + 5 = 1.5(x + 5)

- Simplify the right hand side

∴ 2 x + 5 = 1.5 x + 7.5

- Subtract 1.5 x from both sides

∴ 0.5 x + 5 = 7.5

- Subtract 5 from both sides

∴ 0.5 x = 2.5

- Divide both sides by 0.5

∴ x = 5

∵ x represents the age of Mark now

∴ Mark now is 5 years old

∵ Christina is twice as old as Mark now

∴ Christina is 10 years old

* Christina is 10 years old now