Question

In a certain card game, for every 4 blue cards, there are 3 yellow cards. There are a total of 84 blue and yellow cards in the game. How many blue cards are in the game?

Answer 1

The simplest way to think of this is a ratio. In the original 7 cards used for demonstration, 4 are blue. You can write it like this:

$\frac{4}{7}$

Since there are 84 total cards, and you need to find how many total blue cards there are, you can compare the total of the sample to the complete total, and then solve for an x value of total blue cards.

$\frac{4}{7}$ = $\frac{x}{84}$

You can solve using cross multiplication. 84*4=336. 7*x=336. 

x=48