The ratio of cars to trucks passing a certain intersection is found to be 7:2. If 63 vehicles (cars and trucks) pass he intersection, how many might be trucks?

So, consider the following. The ration is 7:2. This means for every 9 vehicles passing by, 7 are cars and 2 are trucks. Now, since 7 + 2 = 9, we can multiply everything by whatever will make the total equal 63... in this case, 7. Because everything is multiplied by 7, the statement and ratio remain true.

 

49 + 14 = 63

 

So 14 might be trucks, following the ratio.