A line passing through the origin has slope −1. Determine the value of a, if the line is to contain the point (a, −1).
can someone help me please?
Any (non-vertical) line can be written in the form y= mx+ b where m is the slope and b is the "y-intercept"- the y value of the point where the line crosses the y- axis. You are given both of those. Once you have written the correct formula, put y= -1 and solve for x.