Răspuns:
Explicație pas cu pas:
75x/10+90y/100 =49.5
110x/100+120y/100=69.6
3x/4+9y/10 =49.5 numitor 40
11x/10+12y/10 =69.6 '' '' 10
30x+36y=1980
11x+12y=696 I×3
30x+36y=1980
33x+36y=2088 I -
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3x / =108
x=36
30×36 +36y =1980
1080+36y=1980
36y=1980-1080 =900
y=25