Answer:
Slope:

Y intercept: 7
Equation:

Explanation:
The slope is found by doing the equation
. When looking at the first two points, it's shown that the rise (difference between the two y values) is -3 (since it decreased by 3) and the run (difference between the two x values) is 4 (since it increased by 4).
This gives us a slope of
.
The y intercept is found by looking at the y value when x = 0. In this picture, it is clear that it is 7.
The equation you want to use is y = mx + b , where b is the y intercept and m is the slope. Just plug in the numbers and you got your equation!