What is the value of y that solves the system of equations 4x=2y=8 and 4x-y= -1

Answer 1

I will assume a typo and that you meant:
4x + 2y = 8
4x - y = -1
let's just subtract them:
3y = 9
x = 3

now that we know the x, sub that into either one of the other
equations to find y

Answer 2

oops, I found y, not x

so in effect that was your question.