Question

a
4x+2y=10
6x-2y=10

b
4x+10y=28
2x=2y

Answer 1

a) (I) 4x + 2y = 10 
    (II) 6x - 2y = 10 

(I) + (II) 
4x + 6x + 2y - 2y = 10 + 10
10x = 20
x = 2
y = 1

b) (I) 4x + 10y = 28
   (II) 2x = 2y >> x = y

Assim, em (I):
4x + 10x = 28
14x = 28
x = 2
y = 2