when someone says "combine like terms," they mean that if a number has a letter with it and another number does not have a letter or has a different letter, then the first term cannot combine with the second
Let, Harry's age - x then Nick is 7x. After 6 years, Harry is x+6 and Nick is 7x+6 So, 7x+6= 5(x+6)=> 2x = 30-6X = 12 In 6 years, Harry will be 12+6 = 18 years (Ans)