Question

Find the value of x or y so that the line passing through the given points has the given slope. (9, 3), (-6, 7y), m = 3

Alternate coordinate systems
Find the value of x or y so that the line passing through the given points has the given slope. (9, 3), (-6, 7y), $$m = 3$$

2021-03-08
Formula for the slope of a line, given two points on that line slope = $$m = \frac{(y2-y1)}{(x2-x1)}$$
Substituting the known values for this problem and simplifying $$3=\frac{(7y-3)}{(-6-9)}$$
$$3=\frac{(7y-3)}{-15}$$
Cross-multiplying and solving
$$-45=7y-3$$
$$-42=7y$$
$$y=-6$$