Завдання 1402 - 1500 » 1443 (1-4)

Розв’яжіть рівняння: 1) x/3 – x/4 = 2/3; 4x/12 – 3x/12 = 2/3; x/12 = 2/3; x = 8. 2) y/4 = 2y/5 – 21/10; 5y/20 – 8y/20 = – 21/10; – 3y/20 = – 21/10; y = 14. 3) 5x/6 + x/3 = 14; 5x/6 + 2x/(6 ) = 14; 7x/6 = 14; x = 14 ∙ 6 : 7; x = 12. 4) 21 – 2y/5 = y; 5y/5 + 2y/5 = 21; 7y/5 = 21; y = 21 ∙ 5 : 7; y = 15.