Завдання 401 - 500 » 414

Розв’яжіть рівняння: 1) х/28 + 12/7 = 25/28; х/28 = 25/28 – 18/28; х/28 = 133/28 – 18/28; х/28 = 25/28; х = 25; 2) 15/9 – х/81 = 46/81; х/81 = 14/9 – 46/81; х/81 = 126/81 – 46/81; х/81 = 80/81; х = 80; 3) х/6 + 1/8 = 17/24; х/6 = 17/24 – 3/24; х/6 = 31/24 – 3/24; х/6 = 28/24 = 7/6; х = 7; 4) 3/8 – х = 1/4 – 3/20; 3/8 – х = 5/20 – 3/20; 3/8 – х = 2/20; х = 3/8 – 1/10; х = 15/40 – 4/40; х = 11/40; 5) (4/5 – у) + 1/6 = 1/3 – 1/10; (4/5 – у) = 1/3 – 1/10 – 1/6; 4/5 – у = 10/30 – 3/30 – 5/30; 4/5 – у = 1/15; у = 4/5 – 1/15; у = 12/15 – 1/15; у = 11/15.