Answer:
The cost in 2004 was $35.67.
Step-by-step explanation:
This question can be solved by rule of three.
In 2005, the price os $36.78 was a 3.1% increase over the cost in 2004.
So 36.78 is 100+3.1 = 103.1% = 1.031.
The 2004 cost of $x is the equivalent ot 100% = 1.
So
$x - 1
$36.78 - 1.031
[tex]1.031x = 36.78[/tex]
[tex]x = \frac{36.78}{1.031}[/tex]
[tex]x = 35.67[/tex]
The cost in 2004 was $35.67.