1: Which ratios form a preportion?

Question

a 4/9, 12/25
b 3/7, 18/42
c 5/11, 20/45
d 5/8, 15/25***
2: which ratio forms a proportion with 18/30?
a 20/35
b 50/90
c 36/48***
d 60/100
3: which proportion has cross producrts of 5 X 24 and 8 X 15?
a 5/8 = 15/24
b 5/24 = 8/15***
c 8/24 = 15/5
d 15/8 = 5/24

Answer 1

1. Disagree ("preportion"?)
2. 36/60 (typo?) It would help if you proofread your questions before you posted them.
3. Online, “*” is used to indicate multiplication to avoid confusion with “x” as an unknown. Not sure what you are asking.

Answer 2

#3: the cross-product is the outsides = insides
so, ...