A system of equations has 1 solution. If 4 x minus y is equal to 5 is one of the equations, which could be the other equation?

Rewrite 4x − y = 5 as y = 4x − 5, which has slope 4. A system has exactly one solution when the two lines have different slopes, so they intersect once. Choice D, y = −4x + 5, has slope −4 and therefore intersects the given line at one point. Choices A and B describe the same line, while C is a distinct parallel line.

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