Today is Mark's birthday. Four year, from today he will be twice as old as he was 13 years ago. How old is Mark today ?	Choose the most appropriate option.
A) 26 years	B) 27 years	C) 28 years	D) 29 years	E) 30 years
let Mark's age=x
x+4=2(x-13)
x=30
ANSW30 yearsR:30 years
<result>E</result>
Today is Mark's birthday. Four year, from today he will be twice as old as he was 13 years ago. How old is Mark today ?