Bo and Erica are yoga instructors. Between the two of them, they teach 39 yoga classes each week. If Erica teaches 15 fewer than twice as many as Bo, how many classes does each instructor teach per week?
A.
22 Bo; 17 Erica
B.
18 Bo; 21 Erica
C.
15 Bo; 24 Erica
D.
20 Bo; 19 Erica