Question

John is now 10 years older than Marcus. Three times Johns age 5 years from now will be the same age as Marcus age 5 years ago. Write the equation and solve

Answer 1

Now:
Marcus ---- x
John ------ x+10

5 years from now:
John's age = x+15

5 years ago:
Marcus = x-5
3(x+15) = x-5
that would give you the silly answer of x = -25

checking
now Marcus is -25
John is -15

5 years from now, John is -10
and 5 years ago Marcus was -30
sure enough 3 times John's age (or -30) equals Marcus' age .

Mathematically it works, but in reality this question is bogus.
Check your typing or else tell your teacher that the question makes no sense.