A bag contains yellow, green, blue, and white marbles. The ratio of yellow, green, blue, and white marbles is 1:2:3:4. If the bag contains 180 marbles, then how many blue marbles are there?
1 + 2 + 3 + 4 ==10 - sum of all ratios
180 / 10 ==18 - this is the constant.
18 x 1==18 - yellow marbles
18 x 2==36 - green marbles
18 x 3==54 - blue marbles
18 x 4==72 - white marbles.
