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

### Instruction:
Mary, Jess, and Christina want to decorate a party room with balloons. Each person inflates balloons at different speeds, and they only have 30 minutes to inflate as many balloons as possible. Mary inflates 10 balloons per minute, Jess inflates 7 balloons per minute and Christina came 15 minutes late and was the slowest one inflating 4 balloons per minute. How many balloons can they inflate before running out of time?

### Response:
They have a total of 30 minutes * 10 balloons/minute = <<30*10=300>>300 balloons inflated by Mary.
They have a total of 30 minutes * 7 balloons/minute = <<30*7=210>>210 balloons inflated by Jess.
Christina had inflated until the party ended 15 minutes * 4 balloons/minute = <<15*4=60>>60 balloons.
Mary, Jess, and Christina together inflated a total of 300 balloons + 210 balloons + 60 balloons = <<300+210+60=570>>570 balloons
#### 570