human
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?
assistant
How much money did Johnny invest? ** Johnny invested twenty and ten dollars for a total of 20+10=<<20+10=30>>30 dollars invested
How much money did Johnny triple? ** Johnny tripled this amount of money over the year, for a total of 30*=90 dollars
#### 90