To solve this problem you must apply the proccedure shown below:
1. You have that varies jointly as
and
and inversely as the product of
and
. Therefore, you can write the following equation, where
is the constant of proportionality:
2. Now, you must solve for the constant of proportionality, as following:
3. Susbtiute values:
4. Substitute the value of the constant of proportionality into the equation:
The answer is:
ANSWER
The linear equation is: y = 80x + 65
Te cost for 40 football jerseys: $3265
EXPLANATION
Let 'x' be the number of jerseys and 'y' the cost of x jerseys.
Each jersey costs $80, so the cost of x jerseys is 80x. There's also an extra fee for procesing of $65, which is the same no matter how many jerseys they buy.
Therefore, the cost 'y' of x jerseys is:
Now we want to know the cost of 40 football jerseys, so we just have to replace x by 40 and solve: