Answer:
B. -5/4
Step-by-step explanation:
We're going to assume that you don't mean
y = 45x -3
which has a perpendicular line with a slope of -1/45.
Rather, we're going to assume that you mean
y = 4/5x -3
so that the slope of the perpendicular line is -5/4.
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Similarly, we're going to assume that the answer choices are supposed to represent fractions, so that the above slope matches choice B.
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If the slope of a line is m, the slope of the perpendicular line is -1/m. The reciprocal of a fraction is the fraction that has numerator and denominator swapped. -1/(4/5) = -5/4.
