Which equation is in slope-intercept form and represents a line with slope 3 through the point (9,-4)

Slope-intercept form is y = mx +b, where the variable m represents the slope of the line and the variable b represents the y-intercept of the line. Since we weren't given the y-intercept, one way to solve this problem is substitute the slope for the variable m and then the x and y values from the ordered pair to solve for b.

y = mx + b

y = 3x + b

-4 = 3(9) + b

Now, we can simplify by computing the multiplication on the right side of the equation.

-4 = 27 + b

Finally, we can find the value for b by subtracting 27 from both sides of the equation to get:

-31 = b

Now, we should substitute this value for b back into our equation with the slope.

y = 3x - 31

Therefore, your answer is y = 3x - 31.

Hope this helps!