Answer: F=140
Step-by-step explanation:
720=(x-60)+(x-40)+(x-20)+130+120+110
720-130-120-110=3x-120
360=3x-120
360+120=3x
480=3x
480/3=x
160=x
F=160-20
Next problem
102+31+x=180
133+x=180
x=180-133
x=47
