Jake will be represented by variable a.
John will be represented by variable o.
a=o+10
a+5= 2(o+5)
For the second equations, write a literal equation to solve for a.
a+5=2o+10
a=2o+5
Since we have two expressions that equal a, we can tell that the two expressions are equal.
o+10= 2o+5
10=o+5
5=o
We now have the age of John. Plug his age in to find Jake's age.
a=5+10
a=15
Final answer: Jake is 15