X; - x2 = -2,
3x, + 2x, + x3 = 11.
- 4x, - 5x2 + 2xz = -15​

☆ (1 2/9 + 1 1/6) × (2 - 1 25/42) = 2 целых 7/18 × 17/42 = 731/756
▪1) 1 целая 2/9 + 1 целая 1/6= 2 целых + 4/18 + 3/18=2 целых 7/18
▪2) (2 - 1 целая 25/42) = 1 целая 42/42 - 1 целая 25/42 = 17/42
▪3) 2 целых 7/18 × 17/42 = 43/18×17/42= 731/756

☆ (4 + 2 7/15) * (10 - 8 16/23)=5 целых 56/345
▪1) (4 + 2 7/15)= 6 целых 7/15
▪2) (10 - 8 16/23)=9 целых 23/23 - 8 целых 16/23=1 целая 7/23
▪3) 6 целых 7/15 - 1 целая 7/23 = 5 целых (161-105)/345 = 5 целых 56/345

☆ (4 + 5 1/6) * ( 3 2/3 - 13/33)=30
▪1) (4 + 5 1/6) = 9 целых 1/6
▪2) ( 3 2/3 - 13/33) = 3 целых 22/33 - 13/33 = 3 целых 9/33 = 3 целых 3/11
▪ 3) 9 целых 1/6 × 3 целых 3/11 = 55/6 × 36/11 = 5 × 6 = 30

☆ 6 5/12 * 4/11 - 11 4/11 * 1/9=1 целая 7/99
▪1) 6 целых 5/12 × 4/11 = 77/12 × 4/11 = 7/3 × 1/1 = 7/3 = 2 целых 1/3
▪ 2) 11 целых 4/11 × 1/9 = 125/11 × 1/9 = 125/99 = 1 целая 26/99
▪3) 2 целых 1/3 - 1 целая 26/99 = 2 целых 33/99 - 1 целая 26/99 = 1 целая 7/99

10 =  2 * 5
70 = 2 * 5 * 7
НОД (10 и 70) = 2 * 5 = 10
НОК (10 и 70) = 2 * 5 * 7 = 70

22 = 2 * 11
88 = 2 * 2 * 2 * 11 = 2³ * 11
НОД (22 и 88) = 2 * 11 = 22
НОК (22 и 88) = 2³ * 11 = 8 * 11 = 88

25 = 5 * 5 = 5²
75 = 3 * 5 * 5 = 3 * 5²
НОД (25 и 75) = 5 * 5 = 25
НОК (25 и 75) = 5² * 3 = 75

14 = 2 * 7
20 = 2 * 2 * 5 = 2² * 5
НОД (14 и 20) = 2 
НОК (14 и 20) = 2² * 7 * 5 = 4 * 35 = 140

18 = 3 * 3 * 2 = 3² * 2
30 = 2 * 3 * 5 
НОД (18 и 30) = 2 * 3 = 6
НОК (18 и 30) = 3² * 2 * 5 = 9 * 10 = 90

16 = 2 * 2 * 2 * 2 = 2⁴
40 = 2 * 2 * 2 * 5 = 2³ * 5
НОД (16 и 40) = 2 * 2 * 2 = 8
НОК (16 и 40) = 2⁴ * 5 = 16 * 5 = 80