Question 253005
J = S + 35
J+5 = 2*(S+5)

Two equations and two unknowns.  Solve this system of equations:
J = 65
S = 30

Another way: If Jaime is 35 years older than his son now, then he will also be 35 years older than his son 5 years from now.  If Jaime is twice his son's age 5 years from now, then their ages 5 years from now must be 35 and 70.  Therefore, their ages now are 30 and 65.