Question

resolva o sistema
x+y=6
x-y=4

Answer 1

x+y=6 (5+1=6)
x-y=4 (5-1=4)
x=5 y=1

Answer 2

x e igual a 5 e y e igual a 1
x+y=6
x-y=4
corta os dois y (pos e neg)
2x=10
x=10/2=5

subst o x pelo 5 na 1ªeq do ex 
x+y=6
y=6-5=1