Last year the chess club had 20 members. this year the club has 15 members. find the percentage of change and state whether the percent of change is an increase or decrease

15/20=.6 
1-.6=.4
It decreased 40% since last year 

Abit confused about what you mean, but i think you might be referring to slope intercept form: y = mx + bin that case b, or the y intercept is already given.(0,-1)find the slope by using the formulay2 - y1/x2 - x1the final slope will be 4/2, equivalent to 2.now your equation should look like thisy = 4/2x -1sorry if this didn’t you out!