I need help with this math problem

9

Step-by-step explanation:

Perpendicular lines have negative reciprocal slopes. The green line and red line are perpendicular. We know the slope of the green line is -1/9, so we must find the negative reciprocal of -1/9.

Negate

Negate the slope of the green line

-1/9--> 1/9

Reciprocal

To find the reciprocal, flip the numerator and the denominator

1/9--> 9/1

So, the slope of the red line is 9/1, which is equal to 9

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step-by-step explanation: