The function for x=3 is 1

Then we will multiply both sides of the equation by 2 π :
x + π ( 1 - x ) = 0
x + π - π x = 0
x ( 1 - π ) = - π / · ( - 1 )
x ( π - 1 ) = π
x = π / ( π - 1 )

if you have already covered slopes, you could also get it that way, in fact is simpler that way.
I drew it out. Hope this helps.