Can you explain these words Rate, Per, Divide, Unit and the connections you see between them. Thank you very kind!!!

Abcd is a square. what is the measure of angle bac

Pls i’m super dumb and i need with this one it’s due tomorrow

The bottom of ignacio's desktop is 74.5cm from the floor. ignacio's sits in his adjustable chair, and the tops of his legs are 49.3cm from the floor. each clockwise rotation of the knob on the chair raises ignacio's legs by 4.8cm. write an inequality to determine the number of clockwise rotations, r, ignacio could make with the knob without his legs touching the desk