#1 which pair of ratios form a proportion?

a) 5 : 11 and 6 : 12

b) 7 : 13 and 21 : 39

c) 8 : 14 and 24 : 30

d) 10 : 20 and 20 : 30

#2 use a common denominator to determine whether the ratios form a proportion.

6 : 15 and 30 : 80

a) yes. they form a proportion.

b) no. they do not form a proportion.