Resposta :
a) x+y= 15
x-y= 9(+)
---------------
2x =24
X = 24/2
X =12
x + y = 15
12 + y = 15
y = 15-12
y = 3
R.:
X =12; y = 3
b) x= 4y
2x- 7y= 15
2.4y - 7y = 15
8y - 7y = 15
y = 15
X = 4.y
X = 4.15
X = 60
R.:
x = 60; y = 15
a) x+y= 15
x-y= 9(+)
---------------
2x =24
X = 24/2
X =12
x + y = 15
12 + y = 15
y = 15-12
y = 3
R.:
X =12; y = 3
b) x= 4y
2x- 7y= 15
2.4y - 7y = 15
8y - 7y = 15
y = 15
X = 4.y
X = 4.15
X = 60
R.:
x = 60; y = 15