Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
Kris is blowing u balloons for her sister’s party. She has 30 minutes to blow up as many balloons as possible and decides to enlist her brother’s help to increase the number of balloons. Kris can blow up a total of 2 balloon per minute, and her brother works twice as fast. After 15 minutes, her brother doubles his speed and works at this new speed for the remaining 15 minutes. After the 30 minutes, how many balloons, in total, did Kris and her brother blow up?

### Response:
Kris blows up 2 balloons per minute for 30 minutes, blowing a total of 2*30=<<2*30=60>>60 balloons.
Kris’ brother works at double Kris’ speed for the first 15 minutes, blowing up 2*2=<<2*2=4>>4 balloons per minute.
In the first 15 minutes, Kris’ brother blows up 4*15=<<4*15=60>>60 balloons.
After 15 minutes, Kris’ brother doubles his speed, now working at 4*2= <<4*2=8>>8 balloons per minute.
In the second 15 minutes, Kris’ brother blows up 8*15=<<8*15=120>>120 balloons.
In total, Kris and her brother blew up 60+60+120=<<60+60+120=240>>240 balloons.
#### 240