Substitution

s+2k=1
s+k=2

First you subtract the k on both sides. Then substitute 2-k in for the "s" in the first equation.

2-k+2k=1

Add the 2k and the -k together and then subtract the-2 on both sides.

k=-1

Then take this and put in first equation.

s+(-1)=2

Subtract negative one on both sides.

The points will be(1,-1)