Answer:
Part 1) 
Part 2) 
Part 3) 
Step-by-step explanation:
we know that
If two ratios form a proportion, then the two ratios in simplest form are equal
Part 1
Which ratios form a proportion?
<u>case A)</u> 
equate the ratios

------> is not true
therefore
the ratios case A does not form a proportion
<u>case B)</u> 
equate the ratios

------> is true
therefore
the ratios case B form a proportion
<u>case C)</u> 
equate the ratios

------> is not true
therefore
the ratios case C does not form a proportion
<u>case D)</u> 
equate the ratios

------> is not true
therefore
the ratios case D does not form a proportion
Part 2
Which ratio forms a proportion with 18 over 30?
<u>case A)</u> 
equate the ratio to 

------> is not true
therefore
the ratio case A does not form a proportion with 
<u>case B)</u> 
equate the ratio to 

------> is not true
therefore
the ratio case B does not form a proportion with 
<u>case C)</u> 
equate the ratio to 

------> is not true
therefore
the ratio case C does not form a proportion with 
<u>case D)</u> 
equate the ratio to 

------> is true
therefore
the ratio case D form a proportion with 
Part 3
Which proportion has cross products of 5 × 24 and 8 × 15?
<u>case A)</u> 
the cross product is equal to

therefore
the proportion case A is a solution
<u>case B)</u> 
the cross product is equal to

therefore
the proportion case B is not a solution
<u>case C)</u> 
the cross product is equal to

therefore
the proportion case C is not a solution
<u>case D)</u> 
the cross product is equal to

therefore
the proportion case D is not a solution