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?

3

step-by-step explanation:

because where the point where the 2 lines intersect is (3,-1) the x value is 3

step-by-step explanation:

for exempl this   system of equations   y = x - 3

                                                                y = 2x - 5

look   the line : y = x -3     ( red)

                            the line : y = 2x -5 ( bleus)