austin has a collection of 132 baseball and football cards. The cards are in a proportion of 9 baseball cards for every 3 football cards. How many baseball cards does austin have in his collection?

Question

austin has a collection of 132 baseball and football cards. The cards are in a proportion of 9 baseball cards for every 3 football cards. How many baseball cards does austin have in his collection?

Answer 1

The part/part ratio for baseball and football cards is 9:3 or 9/3. The part to whole ratio of baseball cards to total cards (baseball + football) is 9:(9+3) = 9/12 = 3/4. So we have:

3/4 = x/132

where x is the number of baseball cards. Solve for x (hint: cross multiply).