The percentage of the boys at the book fair is 6%
<h3>What is a percentage?</h3>
Percentages are used in mathematics as a decimal ratio expressed in a fraction of 100. It is represented with a symbol known as %.
At a book fair, the ratio of adults to children are:
7 : 3
The total number of people at the book fair = 7 + 3 = 10
The percentage of adults are:

= 70% are adults
The percentage of children are:

= 30% are children
However, if from the children, 4 are girls and 1 is a boy.
The total number of children at the fair = 4 + 1 = 5
The percentage of girls are:

= 24%
The percentage of boys at the book fair is:

= 6%
Learn more about percentages here:
brainly.com/question/24304697