The ratio of orange to brown M&M's in the bag is 4:1
This means that every 5 M&M's, 4 will be orange and 1 will be brown
You can express this ratio as follows:
Expressing the ratios as fractions will allow you to calculate the total number of candies of each colour in the bag, just multiply the total number of candies by the determined fractions:
There are 36 orange candies and 9 brown candies in the bag.