Question

You start out with $20 and then spend money in a store where every item is $3. Y = -3x + 20. What is the slope of this problem?

Answer 1

If Y is the number of dollars you have and X is the number of items you've bought, the slope of the line is -3. (rise over run-> "rise" of -$3 in a run of 1 item.)

Answer 2

The slope-y intercept form of a line is the following:
y = mx + b where m is the slope and b is the y-intercept.

Comparing the given equation:
Y = -3x + 20 to:
Y - mx + b,
you can pick out the slope of -3 as the coefficient of the x term.