Which ratio is equivalent to 5: 4 ?

Think of the ratio 5:4 as 5/4an equivalent ratio is going to be an equivalent fraction. 
5/4 = 10/8 = 15/12 = 20/16...and anything else that is equivalent...and these can be written as ratios 10:8, 15:12, 20:16

Arhombus is a quadrilateral.