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
With the information given we have:

Where W is the weight, k is the proportionality constant and r is the radius of the can's radus. Remember that the weight varies jointly so this key word means that you need to multiply the mentiones parameters by a proportionality constant k.
We simply need to reorganize the expression and isolate k for the frst answer:

Replacing by all the appropiate values we get:

For the second part knowing k we have:
Let "b" represent the number of biscuits Jacky baked.
.. container A holds (3/7)b
.. container B holds (1 -3/7)*(5/8)b = (5/14)b
.. container C holds (1 -3/7 -5/14)b = (3/14)b = 168
Then
.. b = 168/(3/14) = 784
Jacky baked 784 biscuits.
<span>a.2c+6a=148 a+c=38
this is the answer</span>