Answer:
F=140
Step-by-step explanation:
Remember that all angles will be able to add to 720 so you should get something like this:
130+120+110+x-20+x-60+x-40=720
Then solve for x to do this:
130+120+110+x-20+x-60+x-40=720
360-120+3x=720
3x+240=720
3x=480
x=480/3
x=160
With x=160, you can plug in to solve and find that F=140