How do you solve these equations algebraically?

y=x^2+4x
2x-y=1

y=x^2+2x+3
x+y=1

I would use substitution. For instance, the first:

y= x^2+4x
2x- (x^2+4x)=1
x^2-2x+1=0
(x-1)(x-1)=0
x=1 y=5