THIS IS CHALLENGING. THIS WILL DEFINITELY PROVE THAT YOU ARE SMART!!

y = 2x + 13
Positive value:
2x + 13 > 0
2x > -13
x > -6.5
Negative value
2x + 13 < 0
2x < -13
x < -6.5
y=2x+13
y>0 would be a positive value
2x+13>0
subtract 13 from each side
2x >-13
divide by 2
x > -13/2
x > -6 1/2
y < 0 is a negative value
2x+13 < 0
2x<-13
x < -13/2
x < -6 1/2
if x > -6 1/2 it has a positive value
if x< -6 1/2 it has a negative value
x= -6 1/2 it equals 0