Use the slope formula
(y₂ - y₁)/(x₂ - x₁)
Let (0,2) = (x₁, y₁)
Let (3,0) = (x₂, y₂)
Plug into corresponding variables
(0 - 2)/(3 - 0) = -2/3
-2/3 is the slope of the line given
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To find the perpendicular line, flip the slope around and change the sign.
-2/3 becomes 3/2
The perpendicular line's slope is 3/2
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hope this helps