Find the equation of the regression line that we would use to predict cost of attendance at public schools using the 75th percentile ACT math score.

Use the datasets "Public" (https://openstax.org/r/Chapter8 Data-Sets) and "Private" (https://openstax.org/r/Chapter8 Data-Sets), which give many institutions of higher learning in the United States (public institutions in "Public" and private, non-profit institutions in "Private"), the schools' 75th percentiles on the math section of the SAT (SATM75), the verbal section of the SAT (SATV75), the math section of the ACT (ACTM75), and the English section of the ACT (ACTE75). It also gives the schools' admission rates (AdmRate) and total annual cost of attendance (Cost).