Question: Johnny took his allowance of $20 and added an extra $10 to it.  He then invested this sum of money, which tripled in a year.  How much money did he have after a year?
Give me a solution to this problem
Answer: 
Johnny invested twenty and ten dollars for a total of 20+10=30 dollars invested
Johnny tripled this amount of money over the year, for a total of 30*=90 dollars