The y-intercept is where the line starts on a graph. The y-intercept is 35.
This number doesn't change ever in the linear expression.
"45x" represents the slope of the line and "the number of hours it takes to fix the machine." y represents the total cost.
35 is the only value that doesn't get altered in the expression because its by it self.
The first option doesn't make much sense because it represents "45x" not the y-intercept.
The second option makes sense because the cost for looking at the machine doesn't change which represents the starting amount.
The third option doesn't make much sense because the total cost to fix the machine is represented by "y" in the original expression. It even says so in the question, "where y represents the total cost."
The fourth option doesn't make much sense because it has nothing to do with the actual problem it self.
Therefore, the only logical answer is "the service fee for coming to look at the machine."
Best of Luck!