9 м 5 дм=9*10 дм +5 дм=90+5=95 дм
18*100:12=150
75*100:12=625
56*100:8=700
2,7*100:8=33,75
1) 2х + y + 5xy - 5xy = 14 - 9
2x + y = 5
y = 5 - 2x
2) 2x + 5x( 5 - 2x ) = 14
2x + 25x - 10x^2 = 14
10x^2 - 27x + 14 = 0
D = 729 - 560 = 169 ; VD = 13
X1 = ( 27 + 13 ) : 20 = 2
X2 = ( 27 - 13 ) : 20 = 0,7
y = 5 - 2x
y1 = 5 - 4 = 1
y2 = 5 - 1,4 = 3,6
Ответ ( 2 ; 1 ) ; ( 0,7 ; 3,6 )