The recipes within Kayla's H.E.L.P eBooks have been formulated using the Australian Metric System, which uses cups and grams as its primary form of measurement.
A cup is determined by volume, rather than weight.
The water measurement therefore equates to:
1/4 cup = 60 mL
1/2 cup = 125 mL
1 cup = 250 mL
If you are using the Imperial System, the conversion will be as shown below:
60mL = 2 fl oz.
125mL = 4fl oz.
250mL = 8fl oz.