Answer:
So, you'll need 16 cups of brown sugar if you use 24 cups of white sugar.
Explanation:
The ratio of cups of brown sugar to cups of white sugar is:
6:9.
24/x = 9/15
Cross Multiply:
24 * 15 = 360
9 * x = 9x
So, divide;
360/9x = 40
9x/9x = x
x = 40
SO, 24:40 = 9:15
40(Total amount of sugar) - 24(White sugar itself) = 16 cups of brown sugar.
So, you'll need 16 cups of brown sugar if you use 24 cups of white sugar.