proportions means having equal amounts of something when shared
the first ratio are
2/3 and 8/12
equating the two expressions
2/3 = 8/12
introducing cross multiplication
2 x 12 = 3 x 8
24 = 24
this form a proportion coz the left hand side is equal to the right hand side
the second question
3/4 = 9/16
cross multiply
3 x 16 = 4 x 9
48 = 36
48 is not equal to 36, therefore this cannot form a proportion