The equation y=2.54x gives the length y in centimeters corresponding to a length x in inches. what is the length in centimeters of a 1-foot ruler?

The equation given in the question is
y = 2.54 x
In this equation, x is in cm and y is in inches
Size of the ruler = 1 foot 
                          = 12 inches.
Putting the value of 12 inches in the equation, we get
y = 2.54x
   = 2.54 * 12
   = 30.48 cm
From the above deduction, we can conclude that the length of the ruler is 30.48 cm. I hope that this is answer that you were looking for and the answer has come to your desired help.