In seven years, huang will be two times as old as he was last year. how old is he now?
5 years old
8 years old
9 years old
14 years old

We can represent the age he is 'now' with the variable n

we can represent "in seven years" as (n + 7)
and
represent "last year" as (n - 1)

so
"in seven years, huang will be two times as old as he was last year"
would translate to
(n + 7) = 2(n - 1)

to solve for n
first distribute the 2
n + 7 = 2n - 2

subtract n from both sides
7 = n - 2

add 2 to both sides
9 = n

therefore
n = 9
so Huang is currently 9 years old (C)