Peter purchased 14 latest baseball cards for his collection. This increased the size of his collection through 35%. How many baseball cards does Peter now have?

First, you must ?nd out how many baseball cards Peter had originally. Use a proportion to ?nd the original number of baseball cards; part /whole = %/100 the 14 baseball cards that he added to his collection is the part. The whole number of baseball cards is what we are looking for, so call it x.
The % is 35 (the percent of increase); 14/x = 35/100. To solve the proportion, cross-multiply; (14)(100) = 35x. Divide both sides by 35 to solve for x; 1,400/35 = 35x /35= 40. The original number of baseball cards was 40, and 14 more were added to the collection for a total of 54 cards.