67085-к: 90=59397

700· (83400:m) = 420000

(n+10986) ·50=589650

1)

67.085 - k : 90 = 59.397

- k : 90 = 59.397 - 67.085

- k : 90 = - 7.688

k : 90 = 7.688

k = 7.688 * 90

k = 691.920

проверка:

67.085 - 691.920 : 90 = 59.397

67.085 - 7.688 = 59.397

59.397 = 59.397

2)

700 * (83.400 : m) = 420.000

83.400 : m = 420.000 : 700

83.400 : m = 600

m = 83.400 : 600

m = 139

проверка:

700 * (83.400 : 139) = 420.000

700 * 600 = 420.000

3)

(n + 10.986) * 50 = 589.650

n + 10.986 = 589.650 : 50

n + 10.986 = 11.793

n = 11.793 - 10.986

n = 807

проверка:

(807 + 10.986) * 50 = 589.650

11.793 * 50 = 589.650

589.650 = 589.650