The ratio of the number of volleyball to the number of basketballs in the p. e room is 4: 7 .there are 21 basketballs . how many volleyballs are there?

Let volleyball be v and let basketball be b.

v : b = 4 : 7,      b = 21

v : 21 = 4 : 7

v/21 = 4/7

7*v = 4*21

v = 4*21/7

v = 4*3

v = 12

Volleyballs are 12

Hope this helps.