To begin, we need to find the slope of the equation x = 2y + 3. The easiest way to find the slope is to put this equation into slope-intercept form, y=mx+b, where the variable m represents the slope. To do this, we must get the variable y alone on the left side of the equation. First, we subtract 2y from both sides.
x = 2y + 3
-2y + x = 3
Next, we subtract x from both sides.
-2y = -x + 3
Finally, we divide both sides by -2 (there cannot be a coefficient on the variable y in this form).
y = 1/2x + 3
Therefore, the slope of this equation is 1/2. However, we are looking for the slope of a line that is perpendicular to this one. This means that it creates four 90 degree angles where the lines cross, and it has the opposite reciprocal slope.
The opposite reciprocal of 1/2 is -2 (you take the opposite in this case by changing the value from positive to negative, and take the reciprocal by switching the numerator and the denominator).
Thus, your answer is -2.
Hope this helps!