Respuesta :

qt2011
-18.5 = -2 (7f + 7.5)
-18.5 = -2×7f + (-2)×7.5
-18.5 = -14f + (-15)
-18.5 = -14f - 15

add 15 to both sides
-18.5 +15 = -14f - 15 + 15
-3.5 = -14f

f = -3.5/-14 = 0.25