Which of the following proportions is true?

10/15 = 45/50

6/16 = 4/14

30/40 = 24/36

16/28 = 12/21

Answer: 16/28=12/21

This is because once both fractions are simplified, they both equal 4/7.

16/28=4/7 (divide both the numerator and denominator by 4)

12/21=4/7 (divide both the numerator and denominator by 3)

The statement answer is 16/28=12/21.