Question

andrew says that in 15 years, the building he lives in will be twice as old as it was 7 years ago. how old is the building that andrew lives in?

Answer 1

29 years old

Explanation:

let the building current age be x

then in 15 years time the age of the building is x + 15

7 years ago the buildings age is x - 7 and twice as old is 2(x - 7)

equating the expressions

2(x - 7) = x + 15 ← distribute parenthesis on left side

2x - 14 = x + 15 ( subtract x from both sides )

x - 14 = 15 ( add 14 to both sides )

x = 29

the age of the building is 29 years