Which is most likely to be the first step in solving a system of non linear equations by substi tyrion

If the equation is not in y=mx+b form then change it into slope intercept form which is. y= mx+ b

if it is already in slope intercept form substitute the second equation that looks like y= mx+ b in for y in the first equation given

╔═⋄═◇═◈═❖═✧═☆═✧═❖═◈═◇═⋄╗✧   ok, now this, is epic.╚═⋄═◇═◈═❖═✧═☆═✧═❖═◈═◇═⋄╝