Respuesta :

Answer:

[tex]f=278[/tex]

Step-by-step explanation:

[tex]f-81=197[/tex]

Add 81 to both sides:

[tex]f-81+81=197+81[/tex]

[tex]f=278[/tex]

f - 81 = 197
f = 278

Add 81 to both sides to solve for f