Question

Marcello is m years old, and Celia is

6 years younger than Marcello. In 4
years, Marcello will be twice as old
as Celia will be. How old is Marcello
today?

Answer 1

Marcello is 8 years old

Explanation:

Marcello is m , then Celia is m - 6 ( 6 years younger than Marcello )

in 4 years

Marcello is m + 4 and Celia is m - 6 + 4 = m - 2

At this time Marcello is twice as old as Celia , that is

m + 4 = 2(m - 2)

m + 4 = 2m - 4 ( subtract m from both sides )

m - m + 4 = 2m - m - 4 ( simplify )

4 = m - 4 ( add 4 to both sides )

4 + 4 = m - 4 + 4 , that is

8 = m

Marcello is 8 years old.