Kate wants to buy a special pen as a gift for her friend. The pen costs $30, and Kate only has money for a third of that amount. How much more money does she need to buy the pen?
Currently, Kate has only 1/3 * 30 = $<<1/3*30=10>>10.
That means Kate needs 30 - 10 = $<<30-10=20>>20 more to buy the pen.
#### 20