The original formula x-4y=- 1, both sides are x2 at the same time,
Available 2x-8y =-2—> ①
2x+y= 16 —>②
Use ①-② to get -8y-y=-2- 16.
The solution is y=2.
Substituting ②, we can get 2x+2= 16.
The solution is x=7.
I hope I can help you.