Example: y = -2x and y = x + 3 does the point (0,4) make either equation true? substitute it in and find out

Point (0,4) has x coordinate of 0, and y coordinate of 4
x = 0
y = 4
Substitute x with 0 in the equations and evaluate if it would make 4 as the result of y.

First equation
y = -2x
y = -2 × 0
y = 0
The result is not 4, therefore point (0,4) doesn't make the first equation true.

Second equation
y = x + 3
y = 0 + 3
y = 3
The result is not 4, therefore (0,4) doesn't make the second equation true.