Question

Решите уравнение a - 3/7a = 2,8
И еще b - 5/9b = 3,6

Answer 1

a - a * 3/7 = 2,8;
a * 7/7 - a * 3/7 = 28/10;
a * (7/7 - 3/7) = 28/10;
a * 4/7 = 28/10;
a = 28/10 : 4/7 = 28/10 * 7/4 = (28 * 7) / (10 * 4) = (7 * 7) / (10 * 1) = 49/10 = 4,9

Answer 2

9/9b - 5/9b = 3,6; 4/9b = 3,6; b = 36/10 : 4/9 = 36/10 * 9/4 = (36*9)/(10*4) = (9*9)/(10*1) = 8,1