1) 75 × (2×5) = 750
750 × (2×5) = 7500
7500 × (2×5) = 75000
2) 720 : (9×4) = 20
3600 : (9×4) = 100
72 : (9×4) = 2
3) (20×8) × (28×4) = 17 920
11/4=2.75 12/8=1.5 13/5=2.6
jndtns
(1 5/6 - 3/8) * х = 2 1/12
х = 2 1/12 : (1 5/6 - 3/8)
х = 2 1/12 : (1 20/24 - 9/24)
х = 2 1/12 : 1 11/24
х = 25/12 : 35/24
х = 25/12 * 24/35
х = 50/35 = 1 15/35
х = 1 3/7
(5/8 - 1/4) : х = 1/6
х = (5/8 - 1/4) : 1/6
х = (5/8 - 2/8) : 1/6
х = 3/8 : 1/6
х = 3/8 * 6
х = 18/8 = 2 2/8
х = 2 1/4
20х+8=20х-30+15
20х-20х=-30+15-8
<span>х=-23</span>