The slope of the line y=-9x+7 is -9.

The slope of a line can be calculated by taking two points on the line and dividing the change in the y-coordinate by the change in the x-coordinate. For example, if we take the points (0, 7) and (1, -2), we have a change in y of 7-(-2) = 9 and a change in x of 1-0 = 1. Dividing the change in y by the change in x gives us 9/1 = 9, which is the slope of the line.

Alternatively, we can use the slope-intercept form of the equation of a line, y = mx + b, where m is the slope and b is the y-intercept. In this case, the equation of the line is y = -9x + 7, so the slope of the line is -9.