Cindy is four years older than twice Mark's age. Juan is half as old as Cindy. How much years older than Juan is Mark?
Mark --- x
Cindy --- 2x+4
Juan --- (1/2)(2x+4 = x+2
comparing x with (x+2) .....
so Juan is 2 years older than Mark
this will be true for any age of Mark you pick:
e.g. let Juan's age be 10
then Cindy is 24
and Mark will be 12, which is 2 years more than Juan