Answer:
b. One
Explanation:
A (standard-form) linear equation in one variable always has exactly one solution.
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We add the qualifier "standard-form" to eliminate equations of the form
x = x . . . . infinite solutions
or
x = x + a . . . a ≠ 0 . . . . no solutions
When the first of these is put into standard form, it is ...
0 = 0 . . . . no longer a linear equation
When the second of these is put into standard form, it is ...
0 = a . . . . no longer a linear equation in x (and not true, either)
In standard form the given equation is ...
y = 6 . . . . . one solution