Boys make up 100% - 60% = 40% of the total number of students.

The total number of students at the school is 300 / (40/100) = <<300/(40/100)=750>>750 students.

Since 60% of the students are female, there are (60/100) * 750 = <<60/100*750=450>>450 female students.

# Answer

450
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
If 60% of the students at school are girls and the number of boys is 300, how many girls are at the school?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
450
If 60% of the students at school are girls and the number of boys is 300, how many girls are at the school?
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