Highest common factor of -12 and 4 detailed answer plz

Find the solution of this system of equation -7x+y=-20 9x-3y=36

The perimeter of a quarter circle is 14.28 miles. what is the quarter circle's radius?

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?