Answer:
15 years old.
Step-by-step explanation:
Let Jim's age now be one unit (1u).
His uncle's age now is then 4 units.
Jim's age in 10 years = 1u + 10
Jim's uncle's age in 10 years = 4u + 10
In 10 years, Jim's uncle's age will be 20 years more than twice Jim's age.
Twice Jim's age =
[tex]2(1u + 10) = 2u + 20[/tex]
Since Jim's uncle's age is 20 years more than this, we can say that his uncle's age is equal to
[tex]2u + 20 + 20[/tex]
which is equal to
[tex]2u + 40[/tex]
We found out that Jim's uncle's age in 10 years is 4u+10. Hence
[tex]4u + 10 = 2u + 40[/tex]
We subtract 10 from both sides:
[tex]4u = 2u + 30[/tex]
Therefore
[tex]2u = 30[/tex]
and one unit is 15. Hence, Jim's age now is 15.