Ley de signos:
a) (+3).(-5).(+2)
(+3).(-5).(+2)
(-15)(2)
-30 → RPTA
c) (-2).(-7).(-2)
(-2).(-7).(-2)
(14)(-2)
-28 → RPTA
b) (-4).(-1).(+6)
(-4).(-1).(+6)
(4)(6)
24 → RPTA
d) (+5).(-4).(-3)
(+5).(-4).(-3)
(-20)(-3)
60 → RPTA
Espero que te sirva! ^^
Saludos, Math_and_fisic_girl