Ответы и объяснения

2013-09-10T22:32:22+04:00
2013-09-10T22:37:06+04:00
2х-18 = 7.98/19
2x-18=0.42
2x=18+0.42
2x=18.42
x=9.21
проверка 7.98/ (2*9.21-18)=19
7.98/(18.42-18)=19
7.98/0.42=19