Jim's uncle is 4 times as old as his nephew Jim. In 10 years, Jim's uncle age will be 20 years more than twice Jim's age. How old is Jim right now?

Jim is 15 years old now and his uncle is 60 years old. So his uncle is 4 times older than him. After 10 years, Jim will be 25 and his uncle will be 70. Which is 20 years more than the twice of Jim's age. So the answer is 15 years.