Since the given shape is a quadrilateral, all of the angles on the inside have to add up to 360°. So, use what is given to write an equation that is set equal to 360. Your work should look like this:
9x + 14x + 4x + 90 = 360 (Combine like terms)
27x + 90 = 360 (Subtract 90)
27x = 270 (Divide both sides by 27)
x = 10
**** Now that you have what x is equal to, plug x in to the value that was given for angle F and solve for its measure. ********************************
14x
14 (10)
140
Angle F = 140°
