Cal. Educ. Code § 46302

Where in a high school or elementary school four terms of school of at least 12 weeks each are maintained during a fiscal year, and where the course of instruction is so arranged that students may complete a full year’s work in any three terms, the total number of days of pupils attendance shall be divided by the greatest number of days school was actually taught in any three of the four terms, but in no case shall the divisor be less than 175.