Explanation:
equation format: y = mx + b where m is slope and b is the y intercept. 
From the points given we find that it is a horizontal line, which means slope or m = 0. So we know so far:
y = 0x + b or y = b 
The y-intercept occurs where x = 0. This occurs at y = -7. So the equation for these two points: 
EQUATION: y = -7
(Plotted graph attached)