129) 20/(100-25)*100=26 2/3%
130) 200*0.15/0.6=50
Х0= -b/2a=8/2=4
y0= 16-32+3=-13
Ответ: (4;-13)
<span>{3x+5y=16
{2x+3y=9
________
{х+2у=7
{2х+3у=9
</span>_______
{х=7-2у
{ 2(7-2у)+3у=9(*) *14-4у+3у=9; -у=-5; у=5
____________
{у=5
{х=7-2*5
__________-
{y=5
{x=-3
ОТВЕТ: (-3;5)
7ц 50кг-70кг=6ц80кг
6ц80кг:5кг=1ц36кг