How many cups will I need for 30 biscuits if there's 2 cups for every 8 biscuits

If there's 2 cups for every 8 biscuits (not try to be mean, but I really really hate biscuit) there will be 7.5 cups. First, you take 8 and divide it by 2 to find out how many biscuits that 1 cup needs, so 4 biscuits per cup. Last, all you have to do left is take 30 and divide it by 4, which will gives you 7.5. So, for 30 biscuits, you will need 7.5 cups, even though I don't know what cup is it (flour, sugar, salt, water, ...).

divide 30/8 = 3.75

3.75 * 2 = 7.5 cups