Tolong bantu No.3 ya…

A.)
(-3 + 4n – 6) – (7n – 8m + 10)
(-3 + 4n – 6) + (-7n + 8m – 10)
= -3 – 4n -6 -7n + 8m – 10
= -3 -6 -10 -4n – 7n + 8m
= -19 – 11n + 8m
= 8m – 11n – 19

b.)
(15a + 7b – 5c) – (-11a -12b + 13d)
= (15a + 7b -5c) + (11a + 12b – 13d)
= 15a + 7b -5c +11a + 12b – 13d
= 15a + 11a +7b +12b – 5c – 13d
= 26a + 19b – 5c – 13d