До десятых 2,9
до сотых 2,82
до тысячных 2,820
{0.2b = 0.3a-10 |:0.2
{0.2a = 0.3b-35 |:0.2
{b = 1.5a - 50
{a = 1.5b - 175
a = 1.5(1.5a-50) - 175
a = 2.25a - 75 - 175
a - 2.25a = -250
-1.25a = -250
1.25a = 250
a = 250 : 1.25
a = 200
b = 1.5 * 200 - 50 = 250
Ответ: a=200; b=250.
489+с*5=9614
с*5=9614-489
с*5=9125
с=9125:5
с=1825
489+1825*5=9614