Analyzing Steps to Write a Linear Equation
A 5-minute international call costs $2.15 and a 12-minute call costs $3.06. The work shows how to write an equation where x represents the number of minutes, and y represents the total cost of an international call. Analyze the steps of the work to determine if the equation is correct.

1. Point 1: (5, 2.15). Point 2: (12, 3.06). 2. m = StartFraction 12 minus 5 Over 3.06 minus 2.15 EndFraction = StartFraction 7 Over 0.91 EndFraction = 7.69. 3. 5 = 2.15 (7.69) + b. b = negative 11.54. 4. y = 7.69 x minus 11.54.

In which step did Emilia make an error?
In step 2, she substituted the x values for y and the y values for x.
In step 3, she didn’t use an x and y from the same coordinate pair.
In step 4, Emilia solved for the wrong variable.
Emilia did not make an error.