A linear equation has many forms. One is y = mx + b. That is not a linear equation because y is in the denominator.
-3/y = 7 -2x
3/y = 2x - 7
y = 3/(2x-7)
When x is 3.5, y is undefined because the denominator is 0. If you plot it, it's not a line.
A simple rule of thumb is a linear equation cannot have x or y in a denominator.
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