I don't understand what you give me the answer

Extra points! find the missing dimension! need asap

Traffic on saturday, it took ms. torres 24 minutes to drive 20 miles from her home to her office. during friday's rush hour, it took 75 minutes to drive the same distance. a. what was ms. torres's average speed in miles per hour on saturday? b. what was her average speed in miles per hour on friday?

"which statement is necessarily true if bd is an altitude to the hypotenuse of right ? abc? a.) ? adb? ? bdc b.) ? adb~? bdc c.) abbc=acbd d.) ? bac? ? bdc"