Question

Is (5,-1) a solution to the inequality y<-3y+4

Answer 1

To test this, just plug in $-1$ for $y$.  

$y\ \textless \ -3y+4 -1 \ \textless \ 4+4 -1\ \textless \ 8$

So this is true. 

Answer 2

-1<-15+4
-1<-11
No
(5,-1) is not a solution to the inequality