Resolva os sistemas:

a)

x + 3y = 10  

x - 9y = -14

3y + 9y = 10 + 14

12y = 24

y = 2

x + 6 = 10

x = 4

S = (4, 2)

b) x + y = 5  

- x + 2y = 4

3y = 9

y = 3

x + 3 = 5

x = 2

S = (2, 3)