Which ratios form a paportion?

A:4/9, 12/25

B:3/7, 18/42

C:5/11, 20/45

D:5/8, 15.25

A. 4/9 = 12/25

cross multiply

(4) (25) = (9) (12)

100 = 108 ... this does not form a proportion

B. 3/7 = 18/42

cross multiply

(3) (42) = (18) (7)

126 = 126 ... this forms a true proportion <==

C. 5/11 = 20/45

cross multiply

(5) (45) = (11) (20)

225 = 220 ... this does not form a proportion

D. 5/8 = 15/25

cross multiply

(8) (15) = (5) (25)

120 = 125 ... this does not form a proportion