The two science classes 7A and 7B each consist of a number of boys and a number of girls. Each class has exactly 30 students.
The girls in 7A have a mean score of 48. The overall mean across both classes is 60.The mean score across all the girls of both classes is also 60.The 5 girls in 7B have a mean score that is double that of the 15 boys in 7A.
The mean score of the boys in 7B is . What is the value of ?
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