Lets say each jersey cost x,
then 12 jerseys will cost 12x
Total costs will then be 12x + 3, 12x of costs plus $3 of shipping
We already know that the total cost is $99
so 12x + 3 = 99
Now isolate x by subtracting 3 from both sides
12x 3 - 3 = 99 - 3
12x = 96
Now divide both sides by 12 to find x
12/12x = 96/12
x = 8
Each jersey cost $8
Answer: You can use the equation 12x + 3 = 99 to find the cost of each jersey
Hope it helps :)