If bill rides his bike 3 miles to fred's house and then walks with fred the remaining 1 mile to school, it will take him 30 minutes. but if he rides the entire distance, it will take him only 20 minutes. what is his walking and biking speed?

Write an equation of the line given the two points below (write your equation in slope-intercept form, y=mx+b): (-4, 4) and (6, -4)

Simplify the expression. -2/5(10+15m-20n)

The first-serve percentage of a tennis player in a match is normally distributed with a standard deviation of 4.3%. if a sample of 15 random matches of the player is taken, the mean first-serve percentage is found to be 26.4%. what is the margin of error of the sample mean? a. 0.086% b. 0.533% c. 1.11% d. 2.22%