Завдання 601 - 700 » 654 (5-8)

5) 6y : 84 = 4/11 : 8/11; y : 14 = 1/2; y = 1/2 ∙ 14; y = 7. 6) 4,5/27 = 7y/21; y/3 = 1/6; y = 1/6 ∙ 3; y = 1/2. 7) (2x – 1,5) : 21/7 = 12/3 : 5/14; (2x – 1,5) : 15/7 = 5/3 ∙ 14/5; 2x – 1,5 = 5/3 ∙ 14/5 ∙ 15/7; 2x – 1,5 = 10; 2x = 11,5; x = 5,75. 8) 0,84/(7/15) = (0,5y + 2,5)/(3 1/3); 0,5y + 2,5 = (0,84 • 3 1/3)/(7/15); 0,5y + 2,5 = 21/25 ∙ 10/3 ∙ 15/7; 0,5y + 2,5 = 6; 0,5y = 3,5; y = 7.