You have a a recipe for the perfect orange juice, it is:
26 parts Water to 1 Part Orange Juice (26:1).
However overall you only want 20ml of mixed liquid (orange juice and water combined).
What calculation do you carry out in a function/logic format that so that any number can be replaced eg:
Ratio : x : y
Required: z
Hints:
$26$ parts Water to $1$ part Orange Juice make how many parts of mixed liquid?
If $x$ parts mixed liquid is $20$ml then how much liquid is in each part?