The number of dolls that lisa, mia and nina have are in the ratio 6: 4: 7 nina had 21 dolls. how many dolls does lisa have?

Lisa, mia, ninaratio of 6:4:7...added = 17so lisa has 6/17 of the total dollsmia has 4/17 of the total dolls and Nina has 7/17 of the total dolls.

Nina has 21 dollsshe also has 7/17 of the total dolls...
7/17x = 21with x being the total number of dolls
x = 21 / (7/17)
x = 21 * 17/7
x = 357/7
x = 51...so there are 51 total dolls

Lisa : she has 6/17 of the total dolls
6/17 * 51 = 306/17 = 18 dolls <

Mia : she has 4/17 of the total dolls
4/17 * 51 = 204/17 = 12

so in summary, Nina has 21 dolls, Lisa has 18 dolls and Mia has 12 dolls for a total of 51 dolls