During January, Dr. Lewis worked 20 shifts. During February, she worked three times as many shifts as she did during January. During March, she worked half the number of shifts she worked during February. Which equation below describes the number of shifts Dr. Lewis worked in March?
A. shifts = 20 + 3 + 1/2
B. shifts = (20)93)(1/2)
C. shifts = (20)(3) + 1/2
D. shifts = 20 + (3)(1/2)
