The slope-intercept form of the line is:
y = mx + b
Where:
m = slope of the line
b = y-intercept of the line
We need to have both values, that is:
m = the slope
b = the y-intercept
For example, if the slope is -2 and the y-intercept is 7, then the equation is:
y = -2x + 7
Note: There are other possible combinations of data to determine the equation of a line.