Please help me i dont understand S=πr2+πrs

Aretha wanted to gather data about the cost of local bowling leagues in her area. she plotted the data and determined that the average bowling league costs consist of a one-time registration fee and a monthly fee modeled by the equation y = 15x + 20. identify and interpret the y-intercept in this model. the y-intercept is 20. this is the cost per month. the y-intercept is 20. this is the cost of registration. the y-intercept is 15. this is the cost of registration. the y-intercept is 15. this is the cost per month.

A50% increase followed by 33 1/2% decrease

Which steps could be part of the process in algebraically solving the system of equations, y+5x=x^2+10 and y=4x-10