2x + 3y = 7.80
5x + 4y = 13,20
2x +3y = 7,80
x= 7,80 -3y
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2
reeplazo
5x +4y =13,20
5( 7,80 -3y) +4y =13,40
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2
39,00 -15y +4y =13,40
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2
39 -15y + 8y
--------------------- = 13,40
2
39 - 7y = 26,80
39 - 26,80 = 7y
12,2 =7y
12,2 /7 =y
1,7 =y
2x + 3y = 7.80
2x + 3(1,7) =7.8
2x = 7,8 - 5,1
2x = 2,7
x= 1,35