11)
{4c+3p=47,50
{7c+3p=73 lei inmultim -1
{4c+3p=47,50
{-7c-3p=-73
4c-7c+3p-3p=47,50-73
-3c=-25,5 inmukltim -1
3c=25,5
c=25,5/3
c=8,5 lei costa un caiet
din 7c+3p=73 avem
7·8,5+3p=73
59,5+3p=73
3p=73-59,5
3p=13,5
p=13,5/3
p=4,5 lei costa un pix
12)
{4b+6f=288 ·(-1)
{9b+6f=468
{-4b-6f=-288
{9b+6f=468
9b-4b+6f-6f=468-288
5b=180
b=180/5
b=36 deci 1 baiat a sadit 36 flori
din 4b+6f=288 avem
4·36+6f=288
144+6f=288
6f=288-144
6f=144
f=144/6
f=24 deci o f·ata a sadit 24 flori
8 fete au sadit 8x24=192 flori
13)
{3s+6p=306,30 ·(-2)
{7s+12p=682,10
{-6s-12p=-612,60
{7s+12p=682,10
7s-6s+12p-12p=682,10-612,60
s=69,50 lei costa 1m de stofa
din 3s+6p=306,30 avem
3·69,5+6p=306,30
208,50+6p=306,30
6p=306,30-208,50
6p=97,80
p=97,80/6
p=16,0 lei costa 1 m de panza
2m de stofa costa 2·69,50lei=129 lei
16) a+2b=1,08
a=7b
7b+2b=1,08
9b=1,08
b=1,08/9
b=0,12
a=7b=7·0,12=
b=0,84
