Respuesta :

step 1: find slope intercept form using the given point and the slope
y - 14 = 21/2(x - 9)
y - 14 = 21/2x - 94.5
y = 21/2x - 80.5
now plug in your given y value and solve for x
-7 = 21/2x - 80.5
73.5 = 21/2x
x = 7