(2):-7*-3=2 1 2 1*-0.5=- 10.5 - 12*-2.6=3 1.2 - 10.5+3 1.2=20.7

(3):

(1-4 3-8 7- 12 7) divided by (-8 7)

= (1-7 of 8-65438+7 of 02) divided by (-7 of 8))

=(-5/8-65438+7/2) divided by (-7/8)

=(-29/24) times (-8/7)

= 1 and 265438+8/0

(7 out of 8) ÷ (1 and 3 out of 4-7 out of 8-17 out of 2)

=-7/8 (7/4-7/8-65438+7/02)

=-8 7 ÷ 7 ÷ ( 1-8 1- 12 1)

=-65438 in 8+0 ÷ 65438 in 24+0

=-3

Add up to-1 and 2 1, 13.

(4): =-2-3 1- 12 1-3=-4 12 1.