The first three terms of a proportion are 3, 5, and 21, respectively. Find its fourth term.

The first three terms of a proportion are 3, 5, and 21, respectively.

1.	The first three terms of a proportion are 3, 5, and 21, respectively. Find its fourth term.
A.	25
B.	30
C.	35
D.	20
Answer» D. 20