resolva os sistemas de ecuaçoes
a) x+y=9
x-y=7
b) 3x-y=4
x+y=2
c) -2x+y=7
x+3y=0
d) 2x+3y=4
x-y=1
e) x=3+2y
3x-y=4
f) 5x+2y=23
y+2x=10
g) x+2(y-4)=7
4(x+1)+y=29
h) 3x+4(2-y)=2x
11+3(x-1)=-y+1​