Which pair of ratios forms a proportion? (4/5 10/13), (7/8 15/18), and (1/2 14/28)

½ and 14/28  

Step-by-step explanation:

If a pair of ratio forms a proportion, they are equal.

First pair of ratios:

4/5 =10/13

Convert to the least common denominator     (4 × 13)/65 = (10 × 5)/65

                                                                                  52/65 ≠ 50/65

The first pair of ratios is not a proportion.

Second pair of ratios:

7/8 =15/18

Convert to the least common denominator     (7 × 9)/72 = (15 × 4)/72

                                                                                 63/72 ≠ 60/72

The second pair of ratios is not a proportion.

Third pair of ratios:

½ =14/28

Convert to the least common denominator     (1 ×14)/28 = 14/28

                                                                                 14/28  = 14/28

                                                                                       ½ = 14/28

½ and 14/28 form a proportion.

what is the original number? you forgot to add it.