How do you find the percent of decrease a report card grade that goes from 90 to 85?

It’s a 5.56% decrease I think,
Find difference between the two numbers then divide the decreased by the original number and multiply that by 100

Where m is the slope of the line and b is the y-intercept of the line, or the y-coordinate of the point at which the line crosses the y-axis. to write an equation in slope-intercept form, given a graph of that equation, pick two points on the line and use them to find the slope. this is the value of m in the equation.