Casey is deciding which of two landscapers to hire. Each landscaper charges an hourly rate plus a fee for each job.

Casey correctly wrote and solved a system of linear equations by substitution. In his work, he substituted an expression for one variable and solved for the other. This resulted in the equation 5 = 20. What can Casey conclude?

One landscaper charges $20 for 5 hours of work.
One landscaper’s hourly rate is $15 lower than the other landscaper’s.
Both landscapers charge the same hourly rate and the same fee per job.
Both landscapers charge the same hourly rate, but not the same fee per job.