Respuesta :

f = -94/3 hope this helps
faizu
−1/8f−3/4−1/4f=11 
=> −8​​f​​−​ 3/4​​−​​​f/4=11
=> -f/8 - f/4 = 11+ 3/4 
=> -4f/32 - 8f/32 = 44/4 + 3/4 
=> -12f/32 = 47/4
=> - 3f/8 = 47/4
=> - 3f = 47 /4 * 8 
=> -3f = 376/4 = 94
=>  f = -94/3 ..

Hope it helps !!!!