Regression Lines

#1
Can someone please explain this to me

In a random sample of 40 students, the mean number of hours spent studying is 7.5 with a standard deviation of 2.4. If the mean grade received is 74% with a standard deviation of 6 and the correlation between the two is 0.86, the equation of the least square regression line that can be used to estimate the grade of a student based on the number of hours of studying that was done is grade=57.875+2.15hours.

Thank you