You can just plug in one of the points to each equation until you get an equality that is true.
I chose to use (-3,2)
1. 5x+3y=1
5(-3)+3(2)=1
(-15)+ 6 = 1
(-9) = 1 <<<(FALSE)
2. x+5y=3
(-3)+5(2)= 3
(-3)+10= 3
7=3 <<<(FALSE)
3. 3x+5y=1
3(-3) + 5(2)= 1
(-9)+10=1
1=1<<<(TRUE)
So, the correct equation is 3x+5y=1.
Make sense?
